Search

Lightweight double leaf walls have been extensively employed in assembly and large-space buildings. Due to the complex and varied stud configurations in double leaf walls, accurately and efficiently predicting the sound transmission loss (STL) of such structures poses a significant challenge. To support performance-based design workflows, this paper presents an analytical model based on sound transmission path decoupling, enabling architects to quickly predict the STL of commonly used lightweight double leaf wall types, including wooden, steel, and acoustical stud constructions. The paper systematically discusses the impact of different stud configurations on sound insulation performance and reveals the underlying mechanisms of sound bridge effects. Results show that the sound bridge effect arises from the structural sound transmission path introduced by various types of studs in the wall, and optimizing stud configurations is essential for decoupling the two leaves of the wall acoustically. Traditional wooden studs, considered as rigid frames, contribute more to the sound bridge effect compared to steel studs of the same structure. A promising approach involving acoustical studs with rubber sound isolation inserts is proposed, which achieves high-level sound insulation performance while offering significant spatial and construction efficiency advantages. This study provides valuable insights into advancing high-performance, lightweight building partitions and contributes to enhancing indoor soundscapes. [ABSTRACT FROM AUTHOR]

In this paper, three-dimensional nonlinear dynamic finite-element analyses are conducted to examine the effect of soil property variability on the lateral displacement (D) of liquefiable ground reinforced by granular columns. A suite of 20 ground motions is selected from the NGA-West2 database as input. A soil-granular column ground system consisting of an intermediate liquefiable layer is modeled in OpenSees. Both the random variable (RV) and random filed (RF) methods are adopted to model the variability of soil property parameters. Dynamic analyses are then conducted to estimate the earthquake-induced deformation of the soil-granular column system. It is found that modeling the variability of soil parameters based on the RV method generally increases the geometric mean and standard deviation (σlnD) of D for the soil-granular column system. Enlarging the spatial correlation of soil parameters in the RF model brings in a slight increase of the mean D and comparable σlnD values, respectively. Hence, incorporating the spatially correlated soil property parameters may not be necessarily increase the variation of D for the soil-granular column system. Specifically, the statistical distribution of D is more sensitive to the vertical scale of fluctuation rather than the horizontal one. The results presented could aid in addressing the variability issue for performance-based design of granular column-reinforced liquefiable ground in engineering applications. [ABSTRACT FROM AUTHOR]

This paper examines the shaft resistance mobilisation ratio as a predictor of cumulative displacement of small-scale floating and end-bearing energy pile foundations subjected to vertical compressive loads embedded in dry sandy soils. A reduced friction model pile was subjected to different mechanical loads and two long-duration, cyclic heating/recovery temperature changes. The pile, soil and container temperatures, pile strains, and vertical displacements are monitored, analysed, and discussed. The results further validate numerical analyses that propose the shaft resistance mobilisation ratio as a variable to identify thresholds above which permanent cyclic thermo-induced deformations may occur. Overall, the experimentally observed responses indicate incremental deformations as the shaft resistance mobilisation ratio increased. The results also suggest that a mobilisation ratio of 66% could be a potential conservative lower-bound limit that could control the increment of thermal-induced vertical displacements in the long term under free pile head conditions. This suggests that a performance-based design would be a reasonable approach for energy piles, and monitoring programs should be set in the field before loading and thermo-activation. [ABSTRACT FROM AUTHOR]

Eccentrically Braced Frames (EBFs) equipped with steel shear links primarily sustain large deformation demands through inelastic actions in the links, including yielding, bucking, and fracture of the steel plates or weld parts. This failure mode becomes more complex and results in highly nonlinear behavior using Low-Yield-Point (LYP) steels for the construction of the links due to their high strain hardening capacities. The existing analytical models have been presented for links made of normal steel grades, and thus there is a substantial research need for developing an analytical model to capture the actual behavior of links made of LYP steels. To fill this gap, this paper developed both shear-hinge and shear-spring-based models for performance-based evaluation of EBFs equipped with LYP steel shear links, which are more practical models in general-purpose structural analysis programs. The accuracy of the proposed model was assessed by comparing it with existing experimental tests and analytical models. As a result, there is good agreement between the proposed model and test results in terms of initial stiffness, post-yielding stiffness, and strength, which shows significant improvement over existing analytical models. [ABSTRACT FROM AUTHOR]

This paper presents the physics based ground motion synthetics and its earthquake engineering consequences in the National Capital Territory (NCT) Delhi, India due to the Mw8.2 scenario earthquake on the Nahan segment of the western Himalaya. In order to fulfill the aim, a state-of-the-art pseudo-dynamic rupture is implemented in a 3D fourth-order staggered-grid viscoelastic time-domain finite-difference code. The ground motion is simulated in a frequency bandwidth of 0–2.5 Hz at the basement level at 158 locations of the NCT Delhi. The computed transverse component of velocity time series at the basement level is numerically transferred to the free surface taking into account the rheological parameters of the sediment deposit. Upon first inspection, the estimated range of peak ground acceleration, between 0.017–0.12 g, indicates that all the buildings in the NCT Delhi will remain safe in the event of an Mw8.2 Nahan earthquake, provided they are constructed in accordance with Indian building codes. But, the computed acceleration response spectra (Sa) depicts that some of the high-rise buildings of the NCT Delhi may suffer minor damage to collapse under partial or complete double resonance condition due to Sa exceeding the DBE and MCE levels. The obtained range of pseudo-spectral displacements (Sd) reveals the need of performance-based design for high-rise buildings in the NCT Delhi, so that they can withstand under partial or complete double resonance condition during the occurrence of Nahan earthquakes. The developed contour maps of Sa and Sd at different periods can be used for the retrofitting and forced-based and displacement-based designs of the high-rise buildings. [ABSTRACT FROM AUTHOR]

Non-structural elements play a crucial role in the overall seismic performance of buildings, as has been largely demonstrated in recent earthquakes that have stuck densely populated regions. Therefore, the development of performance-based seismic design and assessment methodologies for non-structural elements is becoming an important research topic within earthquake engineering. A crucial aspect in such methodologies is the accurate prediction of the seismic demands acting on non-structural elements in terms of consistent absolute acceleration and relative displacement floor response spectra for the most common types of structural seismic force resisting systems. Masonry-infilled reinforced concrete frames are one of the most common building typologies in high seismicity regions, such as the Mediterranean region. This study proposes a simplified procedure to estimate consistent absolute acceleration and relative displacement floor response spectra in masonry-infilled reinforced concrete frames based on an existing methodology to estimate consistent floor response spectra in bare reinforced concrete frames. Nine archetype masonry-infilled reinforced concrete buildings with different numbers of storeys and arranged with three masonry infill typologies were considered as case-study archetypes, and were used to validate the proposed methodology using nonlinear time history analyses. The proposed procedure can accurately estimate consistent absolute acceleration and relative displacement floor response spectra for masonry-infilled reinforced concrete buildings that respond both in the elastic and nonlinear ranges for all the non-structural period range. The estimates of floor response spectra given by the proposed procedure are fully consistent with the well-known pseudo-spectral relationship for the entire non-structural period range. [ABSTRACT FROM AUTHOR]

This paper presents the performance-based fire safety analysis of steel structures of padel-center built in Nokia, Finland. The analyses are conducted using advanced calculation models (fire simulations using Fire Dynamics Simulator, FDS, and finite element method, FEM, based analyses of the steel frames in elevated temperatures using SAFIR software, including joint analysis) in support with less sophisticated models (critical temperatures of steel members). The following localized fire scenarios are studied: lounge area furniture fire (4 sofas), sporting equipment fire (10 sporting bags filled with flammable clothing), fire during maintenance (scissor lift fire with miscellaneous temporary fire load) and a fire on HVAC balcony near the trusses. The aim of the paper is showcase recent developments in design processes and methods that are in practical use today in performance-based fire design (PBD), to demonstrate that relatively extensive performance-based studies can be (commercially) viable also in relatively small and mundane steel buildings, and to present a fairly robust framework for PBD of similar steel structures. As a result of the performance-based design, most of the steel structures in the case building could be constructed without fire protection, but some critical structures were identified and protected to class R30. The proposed design was approved by the local municipal authorities. [ABSTRACT FROM AUTHOR]

Risk-based design and assessment methods are gaining popularity in performance-based structural fire engineering. These methods usually start by defining a set of hazard scenarios to use as analysis inputs. This approach, proven highly effective for other hazard types such as earthquakes, may not be optimal for fire safety design. Indeed, the strong coupling between the fire phenomenon and structural features enables an ad-hoc design variable selection (and/or optimisation) to reduce fire intensity, making fire scenarios additional design outputs. In addition, such a coupling effect implies that fire scenarios maximising consequences are structure specific. Building on these considerations, this paper discusses the limitations that arise at different analysis steps (i.e., fire-scenario and intensity treatment, identifying fire intensity measures, probabilistic fire hazard analysis, developing fire fragility models, and risk calculation) when using conventional risk-based approaches for design purposes. Furthermore, it compares such approaches with a fire safety design methodology (the Consequence-oriented Fire intensity Optimisation, CFO, approach) that addresses the identified limitations. The potential benefits of integrating the two approaches are also discussed. Finally, the fire design of a simplified steel-girder bridge is introduced as an illustrative example, comparing the consequence metrics and design updating strategies resulting from the two approaches. [ABSTRACT FROM AUTHOR]

Global fire performance of structures in fire is proven to be more advantageous in many cases of engineering practice than the prescriptive fire resistance based on isolated structural member testing. Hybrid fire simulation (HFS) is a novel well-suited method trending in recent years for analysis of global performance of structures in fire. In the principles of this method, the part of a structure which has unknown behavior or is uncertain to be numerically modeled (subjected to fire) would be physically tested, while the rest of the structure is numerically simulated. HFS method enables capturing the beneficial interaction mechanisms evolving between fire-exposed structural members and the adjacent cooler substructure. Due to the continuous temperature increase in a fire test and the existing thermal inertia as well as the rate- and temperature-dependent material behavior of structures exposed to fire, a real-time performance in hybrid fire simulation counts as a necessity. This challenge is more critical for hybrid fire simulations with higher applied heating rates relevant to structural fire engineering. Within scope of this paper, (a) a robust and rigorous approach for real-time HFS is presented; (b) a series of proof-of-concept studies of different hybrid fire simulations with various applied heating rates are carried out for a thermomechanical benchmark problem; (c) the important results of four representative hybrid fire simulations with relevant heating rates to structural fire engineering are discussed; (d) the importance of an appropriate calculation method for stiffness update of the fire-exposed structural member over HFS procedure is highlighted, and e) the precision and accuracy of the applied HFS approach with respect to interface error and real-time degree are evidenced. [ABSTRACT FROM AUTHOR]

The aim of the paper is to propose design tools for pile groups when vertical and moment loads are applied simultaneously. This is done by presenting a method to derive the exact solution for the failure locus in the generalized force space, including a vertical load and a moment with components along two axes, to employ for capacity requirements which helps to get rid of overconservative assumptions usually adopted in design. Moreover, closed-form solutions for performance-based interaction domains are also provided allowing to detect all the combinations of external loads associated with a given value of settlement and/or rotation of the foundation that is extremely useful when the design is ruled by serviceability requirements. The application of these straightforward formulae provides results which are in very good agreement with the more rigorous solutions derived from a numerical procedure developed ad hoc for the problem at hand. [ABSTRACT FROM AUTHOR]

With rapid advances in design methods and structural analysis techniques, computational generative design strategies have been adopted more widely in the field of architecture and engineering. As a performance-based design technique to find out the most efficient structural form, topology optimization provides a powerful tool for designers to explore lightweight and elegant structures. Building on this background, this study proposes an innovative pedestrian bridge design, which covers the process from conceptualization to detailed design implementation. This pedestrian bridge, with a main span of 152 m, needs to meet some unique architectural requirements, while addressing multiple engineering challenges. Aiming to reduce the depth of the girder but still meeting the load-carrying capacity requirements, the superstructure of this bridge adopts a variable-depth spinal-shaped girder in the center of its deck, thus forming an elegant curving facade, from which one pathway cantilevers on either side. At one end of the bridge, given considerable elevation difference between the bridge deck and the ground, a two-level Fibonacci-type spiral-shaped bicycle ramp is provided. The superstructure is supported by a series of organic tree-shaped branching piers resulting from the topology optimization. The ingenious design for the elegant profile of the bicycle ramp generates an enjoyable and dynamic crossing experience, with scenic views in all directions. By virtue of technological innovation, the pedestrian bridge is expected to create an iconic, cost-effective, and low-maintenance solution. A brief overview of the theoretical background of the bi-directional evolutionary structure optimization (BESO) and the multi-material BESO approach is also offered in this paper, while the construction requirements and challenges, conceptual development process, form-finding strategy, detailed design, and construction method of the bridge are presented. [ABSTRACT FROM AUTHOR]

Exposed timber in buildings has proven to have a positive effect on the building's sustainability, occupant wellness, and increases the aesthetic appeal of the building but is currently limited by most building codes mainly due to fire safety concerns. While compartment fire testing can be carried out to prove a design performance, this approach is costly and time consuming. Models predicting the fire dynamics inside mass timber compartment with exposed surfaces were developed over the last years. The charring rate of the timber elements, in these models, is either the charring rate of timber when exposed to standard fire or the displacement of the 300°C isotherm using finite element analysis involving several parameters to be determined. Furthermore, using the 300°C isotherm does not account for the impact of the oxygen concentration on the charring rate. In this study, a two-zone model has been developed to estimate the heat release rate (HRR), the upper-layer temperature and oxygen concentration, and the char depth of the exposed timber elements during compartment fires. The charring rate is determined as a function of the incident heat flux impinging on the surface and the oxygen concentration. Comparing the model predictions to 20 experimental compartment fires with and without exposed timber surfaces shows that the model captures well the general fire dynamic, i.e., HRR and temperature. The char depth predictions are close to the experimental data, while being mostly conservative. Seven limitations and improvements have been discussed and will be considered in future versions of this model. [ABSTRACT FROM AUTHOR]

With the development of performance-based seismic design, the residual displacements of structures have become a key factor in determining the post-earthquake functionality and post-earthquake repair cost. However, the factors affecting the residual displacement responses of the RC structure and the corresponding influence laws have not been uniformly understood. This paper systematically investigates the influence of structural properties and ground motion characteristics on the residual displacements of the RC bridge columns, especially the near-fault pulsed ground motion characteristics. To this end, the ultimate quasi-static residual displacement and the dynamic residual displacement are first defined and introduced. Then, Bouc–Wen models and the finite element models of RC columns are selected as target models, and quasi-static analyses and dynamic time history analyses of the two models are performed to obtain the residual displacement responses. The results show that the structural properties and ground motion characteristics significantly affect the residual displacement responses of the RC bridge columns. The influence laws of structural properties on residual displacement responses of different models obtained by using different analysis methods are inconsistent, and it is also differences in the influence laws when using different residual displacement indexes. Furthermore, the residual displacement responses of the RC columns subjected to near-fault pulsed ground motions are larger compared with ground motions without pulses, and they increase with the increasing of the pulse period. The symmetrical pulsed ground motions result in higher residual displacement demands compared with antisymmetric pulsed ground motions. [ABSTRACT FROM AUTHOR]

Five different design approaches are compared on a single mid-rise reinforced concrete building, pitting two performance-based designs against three conventional methods in delivering a solution that satisfies different sets of performance objectives. Two of the conventional designs stem from the literature, and they represent 2003 IBC compatible solutions. Another employs the yield point spectra to deliver a code-like solution, satisfying the design norms without needing iterations. The final two are based on the yield frequency spectra to offer a design that can satisfy more detailed performance objectives in a single step. Overall, all five methods are shown to deliver what is expected. Conventional methods can safely capture the code requirements, yet they are disadvantaged when treading in beyond-life-safety territory, where Immediate Occupancy or Collapse Prevention objectives cannot be easily satisfied, a problem that is not shared by performance-based approaches. [ABSTRACT FROM AUTHOR]

This study proposes a fire dynamics simulation method for combustion modeling using heat release and toxic gas emission experimental data. The feasibility of the proposed method is verified through simulations of a cable spreading room of a nuclear power plant where a high level of safety is required. In addition to CO and CO2, nine other toxic gases are detected in the simulations, and the toxic effect is assessed considering two aspects. First, the order of toxic gases reaching the toxicity criteria, which is identical to the order of the hazardousness, is assessed. The arrival times to the lowest allowable exposure limits are ranked as CO < NO2 < SO2 < HCl < HCN < HBr < HF < CH2CHCN < HCHO < CO2 < H2S. The arrival time is inversely proportional to the degree of risk. Second, the comprehensive toxicity index (TI) and its time-weighted average are proposed to assess the combined effects of all emissions. The comprehensive TI of combined emissions is substantially larger than that of only CO. This implies that the conventional performance-based design method, typically used to assess the toxic and suffocation effects of only CO, CO2, and O2, may cause considerable error during risk assessment, because it ignores toxic effects of minor gases such as NO2, SO2, HCl, HCN, HBr, HF, CH2CHCN, HCHO, and H2S. The proposed experimental-data-based simulation method enables more advanced fire dynamics simulations for accurately assessing the hazardousness of toxic gases to humans, and thus, it can be used practically for establishing suitable fire emergency response plans and countermeasure strategies. [ABSTRACT FROM AUTHOR]

In the past three decades, fire engineering has experienced fast development worldwide. Fire regulations for building industry were moved from prescriptive description to performance-based specification. This trend started in the UK in the 1980s and spread to other western countries. Hong Kong closely followed the UK development and adopted the approach of performance-based design (PBD) for the Hong Kong International Airport and MTR stations in the early 1990s. The Government of Hong Kong SAR formally recognised the PBD approach in the prescriptive codes of practice in the mid-1990s and developed the performance-based code (PBC) in the 2000s. This PBC was promulgated in 2011. The evolution in fire engineering impacted the fire community in Mainland China. The State Key Laboratory of Fire Science (SKLFS) was established in University of Science and Technology of China (USTC) in 1991. Then fire science and fire engineering stepped into the fast development track. The building industry in Mainland China started to adopt the PBD approach in the early 2000s for the significant developments including large airport terminals, railway and metro stations, super high-rise buildings, and mega commercial centres. However, a structured PBC system is not available within the regulatory framework to date. Adoption of PBD approach is slowing down in recent years. This paper presents a review of fire engineering development in Hong Kong and Mainland China. The review focuses on the development of the PBC in Hong Kong, and the PBD approach and fire research in Mainland China in the past 30 years. [ABSTRACT FROM AUTHOR]

The understanding of the complex soil–pile–raft interaction and their mobilization with the level of settlement is an important aspect for the performance-based design of the combined pile–raft foundation (CPRF). This paper investigates the influence of various interactions governing the load-bearing mechanism of a vertically loaded CPRF using a three-dimensional finite element-based computer program. The soil was modeled using the conventional Mohr–Coulomb elastic-perfectly plastic constitutive relationship and the drained condition was adopted in the analysis. Piles and raft were modeled using embedded beam elements and plate elements respectively. After successful validation of the developed numerical model, extensive numerical simulations were carried out considering a CPRF of different geometries and configurations where the foundation was subjected to incremental settlement boundary conditions. The variation of pile–pile, pile–raft and raft–pile interactions with settlement and their influence in dictating the loads induced within the foundation components were obtained. The analysis results indicated that the settlement levels played an important role in the mobilization of loads and dictating the efficiency of CPRF. Piles within a CPRF were able to mobilize their full capacity at the settlement of 1.5–2% of the raft width. The level of settlement and the spacing between the piles dictated the transition from negative interaction to positive interaction indicating a higher capacity of a CPRF compared to the combined capacities of piles and raft at higher settlement levels. Results suggested the operating settlement of CPRF which may be useful for geotechnical practitioners in making this foundation a cost-effective foundation choice. [ABSTRACT FROM AUTHOR]

An innovative strategy for an optimal design of planar frames able to resist seismic excitations is proposed. The optimal design is performed considering the cross sections of beams and columns as design variables. The procedure is based on genetic algorithms (GA) that are performed according to a nested structure suitable to be implemented in parallel on several computing devices. In particular, this bi-level optimization involves two nested genetic algorithms. The first external one seeks the size of the structural elements of the frame which corresponds to the most performing solution associated with the highest value of an appropriate fitness function. The latter function takes into account, among other considerations, the seismic safety factor and the failure mode that are calculated by means of the second internal algorithm. The proposed procedure aims at representing a prompt performance-based design procedure which observes earthquake engineering principles, that is displacement capacity and energy dissipation, although based on a limit analysis, thus avoiding the need of performing cumbersome nonlinear analyses. The details of the proposed procedure are provided and applications to the seismic design of two frames of different size are described. [ABSTRACT FROM AUTHOR]

This paper presents two facets of rationalizing natural fires in concrete compartments for structural fire safety. The paper proposes the rate of fire growth corresponding to the maximum possible peak temperature in a compartment, followed by an equation to estimate the equivalent severity between the standard and a natural fire using an energy-based approach. Standard fire curves, applied universally for all design conditions may over- or under-predict real compartment fires. Meanwhile, a full-fledged performance-based design is neither practical nor straightforward to employ in every design situation. The Eurocode parametric temperature–time curves enable engineers to account for specific compartment characteristics, including compartment geometry, building materials, fuel load, and ventilation. Given that different structural fire safety design approaches entail varying levels of complexity, this paper presents simple methods to estimate the worst-scenario compartment fire characteristics. Additionally, fire ratings are established only using standard fire curves, necessitating a scientific means of determining an equivalent severity between natural and standard fires. The energy-equivalence approach used in this paper to establish an equivalent fire severity yields more consistent results than traditional equivalent fire severity methods and empirical formulae for concrete compartments. The proposed equations are developed using simulations of compartment fires and provide insights into the ventilation characteristics that result in the worst-case scenario for both the rate of fire growth and the equivalent time. [ABSTRACT FROM AUTHOR]

We use a method based on Uniform Hazard Spectrum (UHS) to compile seismic microzonation maps for the broader area of Novi Sad, a city in Serbia. The maps are intended for use in the performance-based design (PBD) of earthquake-resistant structures. At present, PBD requires the use of two sets of spectral amplitudes, one in which the structure remains linear and the other in which it may respond nonlinearly. These PBD requirements cannot be met by using only one (same) fixed-shape spectrum and scaling by peak ground acceleration alone for varying probabilities of exceedance. The alternative we present in this paper is based on UHS and describes a combined contribution from (a) seismic excitation by local earthquakes, for which region-specific attenuation equations are used, and (b) seismic excitation by large, distant earthquakes, for which different attenuation equations are used. Our maps also take into account the influences of site geology and site soil conditions in a balanced manner. [ABSTRACT FROM AUTHOR]

Quantification of seismic damage to reinforced concrete (RC) members in terms of damages states is important for condition assessment and performance-based seismic design. This paper presents a classification for axially-loaded flexural-dominant well-detailed RC members into clearly-differentiated damage states based on change in failure mode, principles of mechanics, and loss in lateral load capacity. The paper considers extreme fiber compressive strain as the Engineering Response Parameter (ERP) for classification of the damage states. The identification of member damage states based on compressive strain can be very useful for seismic assessment of the existing buildings and performance-based design of new buildings. Published experimentally observed cyclic force–displacement relationships of RC columns have been numerically simulated and are used to develop statistics of compressive strain. These are further used to develop semi-empirical expressions for extreme fiber compressive strain in terms of RC member properties, viz. axial load ratio, longitudinal reinforcement ratio, and confinement reinforcement ratio. It is shown that the proposed expressions accurately predict experimentally observed compressive strain at different damage states. The fragility functions of damage states, that provide the probability of occurrence of the strain limits, are also presented. It is seen that the proposed expressions for strain and their limits accurately identify the damage states on the monotonic stress–strain relationship of confined concrete and validate the use of strain as an ERP. The present study also provides strain limits for different damage states with consistent level of conservatism. [ABSTRACT FROM AUTHOR]

Nowadays, various types of vibration damping systems are being implemented in different buildings to diminish seismic effects on structures. However, engineers are faced with the challenging task of developing an optimum design for structures utilizing a proper type of damping device based on new techniques such as the performance-based design method. Therefore, this research was aimed at developing a multi-objective optimization algorithm by hybridizing the particle swarm optimization (PSO) and gravitational search algorithm (GSA) to obtain an optimum design for structures equipped with vibration damper devices based on the performance-based design method. Then, the developed hybrid algorithm (PSOGSA) would be capable of optimizing the damping system simultaneously with the optimized details of the structural sections, including the steel rebars, by satisfying all the design criteria. For this purpose, a special process for the design of structures equipped with vibration damper devices according to the performance-based design method was developed by considering of a wide range of vibration damping systems. The proposed PSOGSA optimization framework was then implemented to design a 12-storey reinforced concrete structure equipped with different types of dampers to minimize the structural weight while satisfying all the prescribed performance-based design acceptance criteria. The results indicated that the proposed optimization method was able to successfully optimize the details of the structural members as well as the type and properties of the damper, which significantly improved the structural response in terms of the formation of plastic hinges and the structural movements. [ABSTRACT FROM AUTHOR]

In this study, the inelastic displacement ratio (IDR) for far-field earthquake ground motions is statistically evaluated by the modified energy damage indices, known as hysteresis energy to input energy ratio, to estimate the target displacement in performance-based design theory with an energy approach. The suggested damage model can consider the effect of the frequency content, earthquake amplitude, and ground motion duration by accounting for whole energy aspects, including kinematic energy, damping energy, hysteresis energy, and input energy, without complex parameters in its structure. The IDR is statistically determined in six damage levels, four hysteresis models, and 30 periods of vibration by performing 216,000 dynamic analyses on 300 far-field ground motions. Moreover, the effect of the period, magnitude, source-to-site distance, and soil classes are investigated. Hence, a simplified mathematical equation is proposed based on the C DI - T - D I function to estimate the target displacement in different damage levels for performance-based design. Finally, the proposed method and formula are verified by target inelastic displacements gained from dynamic time history analysis. Statistical results showed that the coefficient of variation (COV) is not too high, and the influence of record-to-record characteristics on the IDR ratio is negligible. Additionally, the proposed equation could estimate the inelastic target displacement in different damage levels and periods of vibration appropriately. [ABSTRACT FROM AUTHOR]

Rapid development in residential areas has increased substructure construction, which has become problematic in large cities. Deep excavation induces ground deformations such as lateral movement and vertical settlement in the soil mass adjacent to the excavated site. Adjacent structures and infrastructures necessitate the use of an efficient design method for urban excavation stabilization to restrict the magnitude of ground deformation. Stress-based design for excavation stabilization does not provide sufficient information about the ground deformation and the probable damage to adjacent buildings. The current study endeavored to attain performance-based design by considering top-down construction in the geotechnical conditions of the city of Qom in Iran. Geodetic surveys were applied to monitor field performance using total station TS02. The deviations of gathered data found to be about 3 mm and 3.8 mm which are within monitoring tool accuracy. A numerical model could be calibrated using the result of geodetic studies. By dividing the geotechnical conditions into four geotechnical types and taking the structural elements as variables in the calibrated model, exponential graphs could be drawn to facilitate the design of excavation support systems on the basis of performance. The numerical studies indicated that the Qc-2 layer shows the least pliability of the structural variables because of its inherent stability. The resulting graphs are able to determine the required stiffness of the excavation support systems based on the maximum allowable deformation of adjacent structures under specific geotechnical conditions. [ABSTRACT FROM AUTHOR]

To implement the performance-based seismic design of engineered structures, the failure modes of members must be classified. The classification method of column failure modes is analyzed using data from the Pacific Earthquake Engineering Research Center (PEER). The main factors affecting failure modes of columns include the hoop ratios, longitudinal reinforcement ratios, ratios of transverse reinforcement spacing to section depth, aspect ratios, axial compression ratios, and flexure-shear ratios. This study proposes a data-driven prediction model based on an artificial neural network (ANN) to identify the column failure modes. In this study, 111 groups of data are used, out of which 89 are used as training data and 22 are used as test data, and the ANN prediction model of failure modes is developed. The results show that the proposed method based on ANN is superior to traditional methods in identifying the column failure modes. [ABSTRACT FROM AUTHOR]

Securing distributed device communication is critical because the private industry and the military depend on these resources. One area that adversaries target is the middleware, which is the medium that connects different systems. This paper evaluates a novel security layer, DDS-Cerberus (DDS-C), that protects in-transit data and improves communication efficiency on data-first distribution systems. This research contributes a distributed robotics operating system testbed and designs a multifactorial performance-based experiment to evaluate DDS-C efficiency and security by assessing total packet traffic generated in a robotics network. The performance experiment follows a 2:1 publisher to subscriber node ratio, varying the number of subscribers and publisher nodes from three to eighteen. By categorizing the network traffic from these nodes into either data message, security, or discovery+ with Quality of Service (QoS) best effort and reliable, the mean security traffic from DDS-C has minimal impact to Data Distribution Service (DDS) operations compared to other network traffic. The results reveal that applying DDS-C to a representative distributed network robotics operating system network does not impact performance. [ABSTRACT FROM AUTHOR]

A new tool for seismic design is presented, called Yield Displacement Charts (YDC). As with its predecessors, the Yield Point Spectra (YPS) and the Yield Frequency Spectra (YFS), the YDC concept takes advantage of the simple features of yield displacement (uy), to use uy in a performance-based design instead of a force-based period-dependent approach. A self-contained and comprehensive approach to YPS and YFS is presented, enabling the novel aspect of YDC to be introduced: a tool for a multi-performance objective design that only depends on the location of the structure to be designed. Once the yield displacement chart has been calculated for a particular place, it can be used for the preliminary design of any structure. For a given value of yield displacement, the YFS are obtained from the Yield Displacement Chart. The suitability of the methodology proposed is illustrated by means of a simple case study of a concrete bridge pier. [ABSTRACT FROM AUTHOR]

Pushover analysis technique is a key tool for the performance-based seismic design that has been largely adopted in the new generation of seismic codes. Therefore, more precise and reliable performance predictions are highly demanded. Improved upper-bound (IUB) pushover analysis is one of the advanced nonlinear static procedures (NSPs) that has been recently developed. This procedure adequately estimates the response of regular and tall buildings. In this study, IUB is extended to assess the seismic response of irregular buildings with setbacks. To this end, an adjustment of the IUB lateral load distribution is implemented by integrating a third mode of vibration to control the response of these complex buildings. Fifteen multi-storey steel frames with different types of setbacks including a reference structure are used to test the accuracy of the proposed procedure by comparing its results to those from other NSPs and the nonlinear time history analysis (NTHA). The findings show the superior capacity of the extended IUB in predicting the seismic response of buildings with different levels and types of setbacks. [ABSTRACT FROM AUTHOR]

Pushover analysis has been recommended as a reliable tool to estimate the seismic capacity of the structures. Vertical irregular structures are highly vulnerable during earthquakes due to stiffness irregularity in their elevations. Hence, seismic capacities of these types of structures need to be re-estimated during structural design stage. So, in this paper, an attempt has been made to assess the actual seismic performance of buildings with two common types of vertical irregularities such as; soft story and setback in comparison with regular (reference) building. These types of vertical irregularities are studied in individual cases, combined in one story, and combined in two different stories of the building models, while most previous studies satisfy with individual type of vertical irregularity case in the studied model. In addition, combined vertical irregularity generates extra weak points, which alter the seismic capacities, failure mode mechanism, and performance point location. Three-dimensional numerical models are created to find out significant response demand such as; the variation in periods of vibration, lateral displacement, inter-story drift, pushover curve, and plastic hinges formation. The results showed that vertical irregular buildings are subjected to early damages and have less seismic capacity than regular one. The fundamental time period becomes misleading term in seismic force calculation for vertical geometric irregular buildings and needs to be re-considered. In addition, extra lateral displacement and inter-story drift are passively generated in the vertical irregular buildings due to sudden change in stiffness. Significant negative variation in the pushover curves, ductility ratios, and plastic hinges' formation is observed when combinations of pre-mentioned vertical irregularity cases occur. Buildings with open soft ground story with asymmetric setback should have additional precautions from international codes during structural design stage according to their irregularity ratio. Therefore, response modification/reduction factor (R) may be scaled-down to adapt these negative variation in seismic capacities. [ABSTRACT FROM AUTHOR]

The aim of this study is to compare direct displacement-based design (DDBD) and performance-based plastic design (PBPD) in order to identify more effective design approach for steel moment-resisting frames. To this end, three steel moment-resisting frames with different heights of 4, 8 and 12 stories have been designed using DDBD and PBPD. Although DDBD obtains higher design base shear in comparison with PBPD in high-rise buildings, DDBD leads a lighter structure than PBPD. This is because of significant difference of these design approaches in the design base shear distribution at the height of structure. DDBD approach distributes the base shear such that the design story shear at upper stories is significantly lower. Because of this distribution model, DDBD leads formation of plastic hinges at columns of upper stories, whereas total plastic hinges have been formed at desirable locations in PBPD. To validate the achievement of design performance level, nonlinear time history analysis of steel moment-resisting frames is performed under twenty-two earthquake records. It can be found from the results that PBPD is the efficient design approach for both low-rise and high-rise steel moment frames, whereas the effectiveness of DDBD approach is questioned by increasing the number of stories of structure. [ABSTRACT FROM AUTHOR]

In nonlinear dynamic structural analysis, a suite of pulse-like ground motions is required for the performance-based design of structures near active faults. The dissimilarity in the amplitude and frequency content of the earthquake time series referred to nonstationary properties in temporal and spectral, respectively. An approach is proposed based on the nonstationary properties of the far-field records and the seismological information in an event for simulating pulse-like records. The pulse-like earthquake time history is estimated via the superposition of the residual part of the earthquake with the estimated pulse. The wavelet-based Hilbert transform is utilized to characterize the nonstationary properties, the instantaneous amplitude, and frequencies of far-field records to model residual part. The effects of near-fault and pulse are estimated based on the seismological properties of the region. The validation of the procedure is indicated by comparing simulated time-series, response spectra, and Arias intensity with recorded pulse-like records in two different earthquakes in California; the Mw 6.7 1994 Northridge and the Mw 6.5 1979 Imperial valley. [ABSTRACT FROM AUTHOR]

Probabilistic fire simulation has been gaining interest in performance-based design approach. Very few evaluations on modelling performance can lead to unnecessary simulations which limit the understanding of fire engineering practitioners to select suitable model for a specific fire phenomenon. This study presents comparison of models' capabilities to recreate kitchen fire experiment through probabilistic assessments when there are various possibilities of fire spread can occur within the compartment. Such situation must consider the possible heat release rate curve from previously burning kitchen item, as this will effect on the possibility that other item igniting, and so enhance the intensity of fire. Determination of accumulated heat release rate data is assessed through the use of B-RISK and simplified model. Simulation input employs design fire for single furniture that was characterized through combination of peak growth and exponential decay functions using statistical analysis of fire severity characteristics from collated experimental data. Probabilistic correlation discloses that both models are able to produce results within an acceptable range of fire practice (> 20%), but B-RISK has better representation of possible cumulative heat release rate region than simplified model when more than 58% similarity of fire spread predictions among multiple items is achieved over different boundary ranges. [ABSTRACT FROM AUTHOR]

During the last decades, digital competence has become essential at workplace. Nowadays, it is difficult to find a job where no ICT skills are required. At the same time, there is a lack of ecosystems for adult reskilling in digital competence. Moreover, most of them do not use of a common language and terminology, decreasing the possibilities of being used by a wider public. In addition, the assessment of digital competence cannot be done using simple self-assessment tests, but more complex tools such as simulations or other activities based on real scenarios. Considering this, we designed a performance-based evaluation system following a pragmatic approach based on DigComp framework. We carried out a needs analysis based on expert consultation (63 teleworkers and 82 entrepreneurs) to create an assessment syllabus and implement the assessment modules. Then, we conducted an analysis by experts (n = 21) of the relationship between the content of the tests and the construct it was intended to measure. After refinement, the system was piloted by end-users all over Europe (n = 525). Results confirmed that DigComp was the most appropriate reference when considering the transversality of digital competence, providing researchers with well-defined clear criteria. [ABSTRACT FROM AUTHOR]

A look at the evolution of Seismology and Engineering Construction from the mid-1700s until the mid-1900s is presented to understand the main accomplishments achieved. Then, we perspective the new advancements toward future mitigation of earthquake impacts with a clear proposal for sustainability and ecological challenge. We will concentrate on analysing the phase 1755–1950 because not enough attention has been paid recently to this exciting period. Next, we jump to our days to look into a few significant problems that require the involvement of the scientific, technical and political communities. In particular: (i) We will look into the developments Intensity Scales should pursue to reduce uncertainties since more than 20 years have passed since the last upgrade. Today, the information from new events is much more extensive and reliable than in the past. Several examples will be presented to illustrate how the frequency of motion should be included in the main characteristics/categories (Building typologies and Vulnerabilities; Damage Grade; Quantity definition) and how it could be beneficial to add a few more descriptors to the Scale, namely shaking of objects and sloshing of water in recipients. (ii) We will analyse the lines of development to mitigate earthquake impacts, and respond to present and future needs, concentrating on the new scientific results that are changing seismology from a "back-analyst" science (indirect contribution to earthquake engineering) into a more pro-active one, with direct impact to reduce risks, such as the EEWS, and low-cost instrumentation. And adding to earthquake engineering the revolutionising health monitoring, as a precautious indicator of malfunction of structures, and a rapid system for evaluation of post-earthquakes, complemented with the citizen science. Finally, all these ingredients need to be merged into simple recommendations for which only data mining will be able to extract new reliable information. Five Highlights's for the future: MEMS EEWS Performance-based design Field trips Citizen Science All these new developments under the umbrella of Machine Learning. [ABSTRACT FROM AUTHOR]

On February 6, 2023, two significant earthquakes struck Pazarcık and Elbistan/Kahramanmaraş with magnitudes of 7.7 and 7.6, respectively. These earthquakes are considered the most devastating disaster in Turkey in the last century. According to official records, these earthquakes affected 11 provinces, resulting in the loss of more than 50,000 lives. Additionally, numerous buildings collapsed or became unusable due to the impact of the earthquakes and the schools constitute an important part of these structures. The schools are important facilities that need to be functional and safe following an earthquake. This study contains both post-earthquake field observations and numerical studies for the retrofitted and non-retrofitted schools. It investigates the retrofitted and non-retrofitted conditions of a total of 7 blocks, which consist of 4 different schools located in Kahramanmaraş. It is observed that the retrofitted school buildings weren’t damaged after these earthquakes. The numerical models underwent nonlinear time history analyses using the ETABS program. The ground accelerations used in the analyses were obtained from the nearest station to the school buildings. The analyses yielded several results, including the natural periods, story displacements, story drifts, and seismic energy inputs of the structures. These results were then compared with the field observations to assess their accuracy and validity. With the retrofit application, story displacements, the interstory drifts and seismic energy input have decreased. Both field studies and numerical analyses have shown that even school buildings with insufficient material and engineering services can become resistant to major earthquakes with an appropriate retrofit method. [ABSTRACT FROM AUTHOR]

The most commonly used analysis method in performance-based design (PBD) is nonlinear static analysis (NSA). In unsymmetrical 2D frames, unlike for the symmetrical state, NSA should be performed in two lateral loading directions. This complicates the process of achieving a feasible optimal design in addition to increasing the volume of calculations. In this study, to overcoming this issue, a two-step approach is proposed for the optimal PBD of unsymmetrical 2D steel moment-resisting frames (SMRFs). In this approach, in two independent steps, the structure is analyzed with a lateral loading pattern based on the first mode shape in the positive and negative directions. The implementation of the second step is conditional on the satisfactory completion of the first step. The objective function takes into account the differences between successful and unsuccessful steps. The constraints considered are based on the acceptance criteria for SMRF according to FEMA-356 at each performance level. The effectiveness of the proposed approach has been investigated by employing four meta-heuristic optimization algorithms to determine the optimum design for case studies of SMRF structures having three and nine stories. [ABSTRACT FROM AUTHOR]

A modified energy method is introduced to simplify self-centering structure analysis without using finite-element analysis. In the proposed method, the conventional energy method is modified such that the modification factor is only applied to the elements absorbing energy either by a non-linear behavior or a damper. The method was successfully implemented in two previously designed self-centering structures, analyzed, and tested. In the first structure, a bridge pier previously tested in a shaking table for different hazard levels was evaluated by the proposed method. The six common calculation relations of ductility reduction factors were evaluated for their accuracy. The Newmark–Hall method was more accurate than the other relationships by about 94% for ductility reduction factor estimation. In the second structure, the proposed method was utilized to compare the uplift of an SC-CBF system with the reported result of the shaking table test and numerical analysis under Kobe and Northridge earthquakes. The accuracy of the calculated coefficient in the Kobe earthquake up to the MCE hazard level and the Northridge earthquake up to the DBE hazard level was more than 90%. Therefore, the proposed method significantly reduced the self-centering structures' computation time and analysis and design efforts without compromising accuracy. [ABSTRACT FROM AUTHOR]

The fundamental construct for performance-based design for fire safety in use today has not significantly changed since the early 1990s. While the current construct has seen some success, performance-based design for fire safety is not as broadly accepted as performance-based design approaches in other building-related engineering disciplines. To advance performance-based design for fire safety, it is proposed to move towards a sociotechnical systems approach. This means changing the starting point from a focus on fire safety objectives as a unique property of buildings, infrastructure, or operations, and considering fire safety as one of several sociotechnical objectives. It also means focusing fire safety analysis and design on system attributes which can be controlled through design, and less on variables for which control is unlikely or not possible. As part of this, consideration of fire safety systems performance should be considered in terms of a 'fail-safe' perspective, in which there is less focus on all possible events that could occur, and more on preventing those which could result in unacceptable performance. Evaluation of building fire safety as a sociotechnical systems problem would also need to consider the interactions of all components that contribute to safety over the lifetime of the system, including in-use safety system management and system performance over time. [ABSTRACT FROM AUTHOR]

Degradation of reinforced concrete (RC) structures due to chloride ingress is a common environmental hazard in coastal regions. Performance-based design of cover for marine RC structures can ensure longer service life and, eventually, results in reduced rehabilitation cost of deteriorated structures. Hence, study on performance-based cover design is of significant importance for incorporating such provision within local construction practice of any region. With this end in view, an attempt has been made to measure performance-based cover requirements for marine RC structures made with 36 local concrete mixes of Bangladesh following the full probabilistic approach of fib code. The probabilistic approach was ensured by random selection of different code-specified parameters from generated population samples of each variable parameter using MATLAB functions. The sample population was generated as per recommended statistical distribution of the variable parameters. The mean, standard deviation and 95th percentile values of the obtained cover bands of each mix were determined to evaluate the statistical significance of the corresponding cover distribution. The cover values, determined using randomly selected parameters (probabilistic approach), were compared with the values obtained through deterministic approach by a previous study. It was found that recommending minimum cover values of deemed-to-satisfy guideline or mean value of the probabilistic approach or value from deterministic technique as concrete cover under marine exposure has potential of not covering a significant segment of population domain. Therefore, 95th percentile of measured cover values should be recommended for ensuring design service life of marine RC structures with adequate confidence. [ABSTRACT FROM AUTHOR]

More than 1300 new buildings over 200 m tall have been built since the year 2000, representing 80% of the total number of supertall buildings globally. The proliferation of such challenging architecture in densely populated urban environments has led engineers to question the fitness of the prevalent prescriptive approaches in ensuring the safety of occupants in the event of a fire. This paper proposes a more rational methodology to estimate scientifically appropriate boundary conditions to represent realistic fire scenarios on the structure for more credible simulation of the consequent structural response using an integrated computational tool. An open-source framework, "OpenFIRE" is developed to implement the methodology. OpenFIRE is capable of simulating the whole sequence i.e., development of a fire scenario, heat transfer to the structure, and the thermomechanical response of the structure, through a sequential coupling of CFD tools with FE software. OpenFIRE exploits the capabilities of available tools such as FDS and OpenSEES and integrates them to produce a free, efficient, and open source computational framework which allows to customise and modify the source codes. It can bring structural fire community a step closer towards the adoption of performance-based designs. This framework is validated by comparing the thermal and structural responses of a square hollow section (SHS) steel column under fire with the experimental data. The critical parameters of the fire scenario produced by the framework are found in close agreement with the experimental data. The thermal and structural responses of the SHS column exposed to the developed fire scenario are also validated with test results in terms of structural temperatures, failure modes, and failure load. [ABSTRACT FROM AUTHOR]

This paper presents a seismic topology optimization study of steel braced frames with shape memory alloy (SMA) braces. Optimal SMA-braced frames (SMA-BFs) with either Fe-based SMA or NiTi braces are determined in a performance-based seismic design context. The topology optimization is performed on 5- and 10-story SMA-BFs considering the placement, length, and cross-sectional area of SMA bracing members. Geometric, strength, and performance-based design constraints are considered in the optimization. The seismic response and collapse safety of topologically optimal SMA-BFs are assessed according to the FEMA P695 methodology. A comparative study on the optimal SMA-BFs is also presented in terms of total relative cost, collapse capacity, and peak and residual story drift. The results demonstrate that Fe-based SMA-BFs exhibit higher collapse capacity and more uniform distribution of lateral displacement over the frame height while being more cost-effective than NiTi braced frames. In addition to a lower unit price compared to NiTi, Fe-based SMAs reduce SMA material usage. In frames with Fe-based SMA braces, the SMA usage is reduced by up to 80%. The results highlight the need for using SMAs with larger recoverable strains. [ABSTRACT FROM AUTHOR]

The experiences of past earthquakes show that the moment-resisting reinforced concrete structures suffered damage due to the inherent brittle behaviors of concrete and lack of structural stiffness. The configuration of buckling restrained brace (BRB) in RC frame is widely increased for the development of the reinforced concrete buckling‐restrained braced (RC-BRB) dual system since the implementation of BRBs can significantly improve the dissipative capacity and lateral stiffness of the main reinforced concrete frames. On the other hand, the structural damage amount is strongly related to the induced displacements and deformations during an earthquake. Therefore, the robust design method must take into account the displacement as the main designing parameter to control the damage of the structures. To this end, researchers have proposed the direct displacement-based design (DDBD) method, which employs displacement as a main designing criterion throughout the design process. In this study, a DDBD method for dual RC-BRB frames is developed by considering the ultimate capacity of BRB elements. New yield displacement and stiffness expressions are proposed to determine the characteristics of the equivalent single-degree-of-freedom (SDOF) system. The developed method is evaluated by designing twelve RC-BRB frames corresponding to different storey numbers and two types of BRB configurations. The Numerical model is developed and validated using available experimental data to be used in the nonlinear time-history analysis (NTHA). In order to gauge the performance of the developed DDBD method, the seismic behavior of designed frames subjected to 20 real ground motions is investigated through NTHA procedure. In addition, the expressions for the design displacement profile of the RC-BRB frames are provided as a function of relative height using the average maximum displacements calculated from NTHA outputs. The developed design displacement profile leads to significant improvements in the coefficient of determination, R2, which is increased from 0.69 for low-rise to 0.98 for high-rise frames. The results indicate that the RC-BRB frames designed by the developed DDBD method can successfully achieve the desired performance objectives. Furthermore, the comparison between the estimated results and the corresponding ones obtained from NTHA indicates that the proposed displacement profile expressions can be found to be efficient and effective for estimating the displacements of the RC-BRB dual frames. [ABSTRACT FROM AUTHOR]

In the process of performance-based design of bridges with aseismic bearings, there exist intrinsic trade-off between minimization of the bearing displacement and pier displacement during strong earthquake events. However, difficulty in selecting the optimal parameters of the bearings that satisfy the two objectives arises, in conjunction with considerable computational resource requirements for nonlinear time-history analysis (NTHA). A computationally efficient approach to determine the optimal bearing design parameters by utilizing the stochastic structural response of equivalent linear systems is proposed in this paper. The key idea is to use the assumed optimal parameters obtained from a stochastic model as the approximation of the exact optimal parameters found from a deterministic model. The stochastic model allows rapid exploration of optimal parameter candidates. A computationally intensive deterministic model is used to determine the performance-based optimal design by performing NTHA only for the design parameter candidates obtained by exploiting the stochastic model. Compared with the exhaustive search approach, the required number of NTHA cases in this method can be significantly reduced. As a numerical example, the proposed method is applied to optimal parameter selection of two slide type bearings in a girder bridge, namely the uplifting slide shoe and the functionally discrete bearings. The seismic performance indices of the bridge with the design parameters determined by the proposed procedure are shown to be almost equivalent to the optimal values found by the exhaustive search approach. An extended parameter search algorithm is incorporated with the proposed procedure for refinement of the assessment at the slightly increased cost of computation. [ABSTRACT FROM AUTHOR]

This paper presents a parametric study of the optimization design for T-shaped deep cement mixing (TDM) and conventional deep cement mixing (DCM) columns improved soft soil for supporting embankments. The objective of the optimization was to find the best compromised solution for the cost effectiveness in conjunction with minimizing the serviceability limit state (SLS) requirements (i.e., settlements, differential settlements, and lateral movements) while maximizing the ultimate limit state (ULS) requirement (i.e., factor of safety against bending failure). A combination between a genetic algorithm and the response surface method was employed as an optimization approach for determining the optimal solution. The relations and interpretations between design column parameters and design requirements are presented and discussed through parametric studies. The optimization results indicate that the optimal TDM column can allow to permit a lower construction cost than the optimal DCM one. [ABSTRACT FROM AUTHOR]

The performance-based optimum seismic design of steel frames is one of the most complicated and computationally demanding structural optimization problems. Metaheuristic optimization methods have been successfully used for solving engineering design problems over the last three decades. A very recently developed metaheuristic method called school-based optimization (SBO) will be utilized in the performance-based optimum seismic design of steel frames for the first time in this study. The SBO actually is an improved/enhanced version of teaching–learning-based optimization (TLBO), which mimics the teaching and learning process in a class where learners interact with the teacher and between themselves. Ad hoc strategies are adopted in order to minimize the computational cost of SBO results. The objective of the optimization problem is to minimize the weight of steel frames under interstory drift and strength constraints. Three steel frames previously designed by different metaheuristic methods including particle swarm optimization, improved quantum particle swarm optimization, firefly and modified firefly algorithms, teaching–learning-based optimization, and JAYA algorithm are used as benchmark optimization examples to verify the efficiency and robustness of the present SBO algorithm. Optimization results are compared with those of other state-of-the-art metaheuristic algorithms in terms of minimum structural weight, convergence speed, and several statistical parameters. Remarkably, in all test problems, SBO finds lighter designs with less computational effort than the TLBO and other methods available in metaheuristic optimization literature. [ABSTRACT FROM AUTHOR]

This paper presents a practical multi-level performance-based optimisation method of nonlinear viscous dampers (NVDs) for seismic retrofit of existing substandard steel frames. A Maxwell model is adopted to simulate the behaviour of the combined damper-supporting brace system, with a fractional power-law force–velocity relationship for the NVDs, while a distributed-plasticity fibre-based section approach is used to model the beam-column members thus incorporating the nonlinearity of the parent steel frame in the design process. The optimum height-wise distribution of the damping coefficients of NVDs satisfying given performance requirements is identified via a uniform damage distribution (UDD) design philosophy. The efficiency of the proposed multi-level performance-based design optimisation is illustrated through nonlinear time-history analysis of 3-, 7- and 12-storey steel frames under both artificial and natural spectrum-compatible earthquakes. Sensitivity analysis is performed to investigate the effects of initial height-wise damping distribution, convergence factor and uncertainty in design ground-motion prediction on the optimisation strategy. The efficiency of the final optimum design solution is also investigated by using drift-based, velocity-based, and energy-based UDD approaches to identify the most efficient performance index parameter for optimisation purposes. It is found that regardless of the selected performance parameter, the optimum damping distribution identified by the proposed methodology leads to frames exhibiting lower maximum inter-storey drift, local damage (maximum plastic rotation) and global damage index compared to an equal-cost uniform damping distribution. However, using drift-based UDD approach generally results in a better seismic performance. It is shown that the proposed UDD optimisation method can be efficiently used to satisfy multiple performance objectives at different intensity levels of the earthquake excitation, in line with performance-based design recommendations of current seismic codes. The proposed method is easy to implement for practical design purposes and represents a simple yet efficient tool for optimum seismic retrofit of steel frames with NVDs. [ABSTRACT FROM AUTHOR]

Controlled rocking steel braced frames (CRSBFs) are modern systems for resilient building structures known for their effective energy dissipation and self-centering features. In a CRSBF, post-tensioned (PT) strands and shear fuses are the distinct features providing the self-centering and energy dissipation mechanisms. As a relatively new structural system, there is a need to study this system's optimal design. Control co-design has gained interest in recent years as a class of integrated engineering system design methods as an alternative to the traditional approach of optimizing the structural design and sequentially optimizing the control system's design. It considers the direct relationship between physical and control system design decisions to discover non-obvious design solutions that enable new performance and functionality levels. This paper proposes a performance-based control co-design methodology for building structures integrating CRSBFs that concurrently minimizes the mainframe weight and determines the CRSBF design parameters subject to design code requirements as the optimization constraints. The patented neural dynamic model of Adeli and Park is used in this research to solve the nonlinear optimization problem. The seismic performance evaluation of the proposed methodology includes a shear frame and a nonlinear 6-story 3D building structure. The 6-story building model consists of 282 nodes with 1,692 degrees of freedom. A total of 610 frame elements, 8 PT strands with nonlinear material, and 32 nonlinear links are determined without requiring high-performance computing. Results show that the energy dissipation mechanism effectively reduces the seismic demand in structural members. The proposed performance-based control co-design methodology can lead to 21% reduction in the total weight of the 6-story frame structure. [ABSTRACT FROM AUTHOR]

In this paper, post-earthquake fire modeling was studied in steel structures with different levels of ground motion intensity. Three-story structure modeling was implemented under post-earthquake fire by using the OpenSees software. The performance of the structure was investigated under different levels of ground motion intensity to the level of life safety. The structure was subjected to seismic and thermal analysis by applying standard fire load up to 880 s of fire. The 9-point thermal gradient for beam and column profiles under heat was analyzed by heat transfer analysis in the software. By comparing obtained results from the seismic analysis and post-earthquake fire analysis, it can be seen that for different levels of ground motion intensity, the behavior of the structure is different when it is exposed to post-earthquake fire than being exposed to the earthquake alone, which can affect the performance-based design of the structure. Therefore, in the design of structures, the effect of post-earthquake fire should be taken into account, considering the seismic zone of the structure and the time required to extinguish the fire. [ABSTRACT FROM AUTHOR]