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The special collection on Twenty Years of Advances in Disproportionate Collapse Research and Best Practices since 9/11/2001 is available in the ASCE Library (https://ascelibrary.org/jsendh/twenty years disproportionate collapse). Kong et al. ([8]) report their experimental and numerical findings on the progressive collapse behavior of scaled six-column subframe composite floor systems subjected to the removal of a side column. Beck et al. ([2]) target optimal required ratios of column-to-beam strengths in column loss situations, considering several failure modes and providing conceptual design recommendations to mitigate disproportionate collapse of frame structures. Three papers focus on advances in analysis and design methods for disproportionate collapse ([2]; [7]; [18]) and show that their limitations no longer are a barrier to disproportionate collapse-resistant design that they once were. [Extracted from the article]

The 2010–2011 Canterbury earthquake sequence highlighted the vulnerability of New Zealand light-frame wood buildings that are the predominant typology in residential construction. While life-safety performance was excellent, many buildings experienced widespread cracking of internal wall linings that resulted in costly repairs and disruption. Despite the widespread use of light-frame wood construction in New Zealand, no known shake table tests have been documented for this construction typology. Additionally, New Zealand light-frame wood building performance cannot simply be inferred from international testing because New Zealand adopts a different design philosophy from those of the US and Canada by relying on gypsum sheathing as the primary lateral resisting element. To further investigate New Zealand light-frame wood building performance, this paper discusses shake table testing of a light-frame wood building specimen, constructed on the University of Canterbury unidirectional shake table using modern New Zealand design and construction approaches. The observed damages during the tests were consistent with those observed in similarly built structures that were investigated after the 2010–2011 Canterbury earthquake sequence. This paper also presents a modeling approach using the state-of-the-art software Timber3D, which was verified by simulating the shake table specimen and comparing the observed and predicted dynamic response from the test specimen and model, respectively. The Timber3D modeling approach included analysis and parameterization of screw-slip data using the Evolutionary Parameter Hysteretic Model, formulation of two-dimensional wall component models, and nonlinear time history analysis of a three-dimensional model of the shake table specimen. The model was shown to reasonably predict the displacement response of the shake table specimen and the strength degradation from cracking damage through repeated earthquakes. The modeling approach described is intended to further the development of residential building models toward the performance-based seismic design of light-frame wood buildings in New Zealand. [ABSTRACT FROM AUTHOR]

Interstory drift response is one of most important quantities to quickly assess performance and damages in buildings. Nevertheless, direct measurement of interstory drift is difficult and expensive, because a stationary reference is required to attach measurement devices. With the goal of accurate and fast reference-free estimation, this paper proposes a new strategy to determine dynamic interstory drifts using accelerations. In particular, a Tikhonov regularization is adopted in a generalized minimization problem to achieve an efficient and stable finite impulse response (FIR) filter. Furthermore, due to independent clocks in wireless sensors, accurate time synchronization of the records is critical; consequently, a strategy for accurate synchronization is also presented. Finally, the proposed strategy has been deployed on edge devices for onboard real-time interstory drift estimation. The proposed method for dynamic interstory drift estimation is validated, first, by numerical simulation using earthquake records as base excitation of linear and nonlinear buildings, as well as through laboratory shake table experiments. Both numerical and lab test results show good agreement of dynamic interstory drifts between the measured value and estimated results, demonstrating the efficacy of the proposed method to estimate the dynamic displacements of seismically excited structures. [ABSTRACT FROM AUTHOR]

This paper presents an extensive numerical study on the seismic performance of steel eccentrically braced frames (EBFs) designed according to the ASCE 7-16 standard. A series of EBF building structures ranging from 2 to 12 stories located in downtown Los Angeles are designed with different yielding links, including conventional and replaceable links. The performance of the structures is investigated through nonlinear time-history analyses (NLTHAs) under a suite of 40 ground motions, selected and scaled to match the target uniform hazard spectrum. The peak deformations are first examined to assess the performance of the buildings as well as the design procedure. Residual deformations are also evaluated and critically compared with acceptable limits, to provide insight into the downtime and recovery time of EBFs after major earthquakes. Previous studies have demonstrated that the response of stable yielding systems to major earthquakes is often accompanied by significant residual deformations, and that residual drifts exceeding 0.5% can cause hindrance to the buildings occupants. In EBFs, in addition to residual drifts, residual link rotations are also relevant and expected to be more severe due to the localization of inelastic deformations in the yielding link. For replaceable modular yielding links, significant residual link rotations after major earthquakes will hinder repairs and the link replacement process, which is one of the important design objectives. The performance of EBFs is also compared with what was observed in previous studies for buckling restrained braced frames and special moment resisting frames. In the end, the results from the extensive NLTHAs are used to establish a relationship between peak drifts and peak link rotations in EBFs. [ABSTRACT FROM AUTHOR]

Mitigating tornado damage remains a critical challenge for communities throughout much of the United States. Enhanced construction techniques typically used in hurricane-prone regions are often recommended as at least part of the solution, but the effectiveness of these techniques lacks empirical evaluation. This study investigates the performance of modern wood-frame residential structures in Arabi, LA, constructed to hurricane-resistant standards, that were impacted by a strong tornado on March 22, 2022. Field teams deployed beginning March 25, 2022, just three days after the tornado touched down, capturing perishable data on the building performance using vehicle-mounted surface-level panoramic cameras, forensic engineering investigations, and unmanned aerial systems. This paper describes the field deployments and identifies common failure mechanisms observed by the field teams. Analytical fragility functions are developed based on the load path observations and compared to empirical fragility functions generated from linking the building performance observations with wind speed estimates at each building derived from a parametric wind field model conditioned to tree-fall patterns. The study finds that despite the frequent use of hurricane-resistant hardware, such as hurricane straps and anchor bolts, key weak links elsewhere in the load path compromised the resistance and led to premature failures. The agreement between the empirically- and analytically-derived fragility functions was lacking, demonstrating the challenges that remain in understanding near-surface tornado wind loading and structural response. Nonetheless, the study provides a consensus framework for future tornado assessments that can help improve our understanding of tornado loading through the utilization of reconnaissance data. Further, the study findings on deficiencies in the load paths of homes in hurricane-prone regions have practical value to risk assessments and future construction practices. [ABSTRACT FROM AUTHOR]

Six of these papers focus on ultrahigh-performance concrete (UHPC) while five papers focus on high-strength concrete (HSC) or high-strength reinforcing (HSR) steel materials. Yang and Okumus ([11]) describe a parametric numerical investigation on the seismic behavior of UHPC rectangular hollow bridge columns with HSR steel for confinement. In this paper, the results from seven column test specimens demonstrate that the ductility capacity of UHPC-jacketed columns can be increased through textile reinforcing. [Extracted from the article]

This paper presents the results of full-scale blast load testing of partially grouted single-wythe and multiwythe insulated masonry walls. Three design sections were evaluated, as follows: (1) a 150-mm (6-in.) standard block masonry wall reinforced with 10-mm (No. 3) rebar at 80-cm (32-in.) maximum spacing, (2) a 200-mm (8-in.) standard block masonry wall reinforced with 13-mm (No. 4) rebar at 122-cm (48-in.) maximum spacing, and (3) a cavity wall consisting of 200-mm (8-in.) standard reinforced concrete masonry unit (CMU) wythe plus a 102-cm (4-in.) clay facing brick veneer with 52-mm (2-in.) thick extruded polystyrene rigid board insulation and a 25-mm (1-in.) air gap between the structural wythe and the veneer. Each test panel was 285 cm (112 in.), seven blocks, in width x 345 cm (136 in.), 17 courses, in height. Only the cells containing reinforcement were grouted. Three blast load experiments were conducted; each experiment tested one each of the three test panel designs. The loading varied significantly between each of the three experiments. Dynamic displacement at several locations through the height (quarter points) of each panel was recorded. The reflected pressures, free field pressures, and internal pressures were recorded at several locations. Interior and exterior videography was also used to record the response. A detailed posttest forensic evaluation was conducted to determine predominant failure mechanisms. The measured transient deflection responses were then compared to analytical responses calculated using the static resistance functions generated from the test results presented in the companion paper as well as by typical blast design methodologies. The comparisons demonstrated that the design resistances used in blast analysis single degree of freedom methodology are conservative. However, the blast testing demonstrated that potentially dangerous modes of localized failure between the grouted cells can occur at scaled distances that are significantly greater than scaled distances that would be assumed to cause breaching. [ABSTRACT FROM AUTHOR]

Trenchless rehabilitation techniques such as cured-in-place pipe (CIPP) had been adopted by many municipalities in the province of Quebec to renew their aging sewer systems. Currently CIPP represents the largest market share of the utilized trenchless rehabilitation techniques in the province of Quebec. Considerable funding is being directed towards sewer systems rehabilitation projects. However, there have been little studies on the performance of the rehabilitated sewers, expected life of the liner, and its structural properties. Therefore, in an effort to address this shortcoming, this paper presents the outcome of a destructive testing protocol conducted on liners samples extracted from sewers rehabilitated using CIPP. Samples used in the testing process were collected from two locations in the sewer network that were rehabilitated over 1 decade ago. Testing the liner included examining the physical properties (e.g., thickness, annular gap, and so on), flexural properties, and tensile properties. The results demonstrate excellent current structural properties and strongly indicate that the liner will meet the anticipated lifetime. Deterioration of liner is expected to take place at a low rate. This conclusion remains valid as long as the current factors influencing structural properties do not change drastically over time. [ABSTRACT FROM AUTHOR]

This paper presents the results of large-deflection resistance testing of partially grouted single-wythe and multiwythe insulated masonry walls. Three design sections were evaluated under uniform pressure in a vacuum chamber test, as follows: (1) 150-mm (6-in.) standard block masonry wall reinforced with 10-mm (No. 3) rebar at 80-cm (32-in.) maximum spacing; (2) 200-mm (8-in.) standard block masonry wall reinforced with 13-mm (No. 4) rebar at 120-cm (48-in.) maximum spacing; and (3) a cavity wall consisting of 200-mm (8-in.) standard reinforced concrete masonry unit (CMU) wythe, a 100-mm (4-in.) clay facing brick veneer with 50-mm (2-in.)-thick extruded polystyrene rigid board insulation, and a 25-mm (1-in.) air gap between the structural wythe and the veneer. Each test panel was 3.5-mð136-in:Þwide x 3.0-mð116-in:Þ high with only the cells containing reinforcement grouted. Displacement at several locations through the height and width of each panel were recorded as each test panel was loaded to collapse. Interior and exterior videography was also used to record the progression of cracking and failure. The failure mechanisms demonstrated the expected tension cracking due to flexure and a ductile flexural response was observed with rotations up to approximately 20°. The resistance function results were plotted and assessed against the resistance definitions assumed by commonly used blast design methodologies, and it was demonstrated that the flexural design resistances used in blast analysis single degree of freedom methodology are conservative. Furthermore, since the 200-mm (8-in.) thick single-wythe wall and the veneer wall had the same structural wythe designs, the stabilizing effects provided by the clay brick veneer and cavity wall components was demonstrated. The resistances and failure modes will subsequently be compared in the companion paper against those encountered in full-scale blast tests involving the same masonry panel designs. [ABSTRACT FROM AUTHOR]

Aftershock ground motions are essential for the study of aftershock synthesis into seismic risk. However, the number of available aftershock records is limited, which necessitates that the methods for synthesizing aftershocks to be developed. This paper aims to propose a methodology to synthesize aftershocks based on the information of the mainshocks, which is able to incorporate the uncertainties of ground motions and can be utilized in seismic risk analysis. The proposed method is illustrated by application to risk analysis for two nonductile RC frame buildings and is validated by comparing with the results obtained from using as-recorded mainshock-aftershock (MS-AS) sequences. The results calculated when only mainshocks are considered are also studied to investigate the MS-AS effects. The paper shows that the synthesized MS-AS sequences using the proposed method can yield results statistically close to the as-recorded sequences. The results also reveal that only considering the mainshock will underestimate the seismic risk but the underestimation is limited. [ABSTRACT FROM AUTHOR]

The retrofit of wood-frame residential buildings is a relatively effective strategy to mitigate damage caused by windstorms. However, little is known about the effect of modifying building performance for intense events such as a tornado and the subsequent social and economic impacts that result at the community level following an event. This paper presents a method that enables a community to select residential building performance levels representative of either retrofitting or adopting a new design code that computes target community metrics for the effects on the economy and population. Although not a full risk analysis, a series of generic tornado scenarios for different Enhanced Fujita (EF) ratings are simulated, and five resilience metrics are assigned to represent community goals based on economic and population stability. To accomplish this, the functionality of the buildings following the simulated tornado is used as input to a computable general equilibrium (CGE) economics model that predicts household income, employment, and domestic supply at the community level. Population dislocation as a function of building damage and detailed sociodemographic US census-based data is also predicted and serves as a core community resilience metric. Finally, this proposed methodology demonstrates how the metrics can help meet community-level resilience objectives for decision support based on a level of design code improvement or retrofit level. The method is demonstrated for Joplin, Missouri. All analyses and data have been developed and made available on the open-source IN-CORE modeling environment. The proposed multidisciplinary methodology requires continued research to characterize the uncertainty in the decision support results. [ABSTRACT FROM AUTHOR]

Building-performance assessment is receiving increased attention within the building industry because of the European Union's (EU's) targets to improve energy efficiency and to increase the use of renewable energy technologies. In this context, there is great emphasis placed on the existing building stock as having a huge environmental impact. The continuous assessment of the energy performance of existing buildings comes into focus to ensure the intended performance and operation during the building life cycle. This paper introduces the Energy Performance Integration in Public Corporate Real Estate Management (EPI-CREM) initiative that aims to improve the energy performance and rational use of energy across the public building stock in Europe by embedding energy-saving measures into the existing public corporate real estate management (REM) processes. To this end, EPI-CREM focuses on the integration of energy-improving actions into the long-term maintenance plans of existing buildings. In this paper, the EPI-CREM method and supporting tools are discussed from a functional point of view, followed by an evaluation of the method based on the results of its implementation on pilot buildings in three participating EU countries. [ABSTRACT FROM AUTHOR]

Although post-occupancy evaluation (POE) is an old tool with hundreds of studies, it is yet to become routine in the housing industry. The growing complexity of buildings and emerging trends in the industry further reinforces the need to carry out more POE studies. Though some studies exist, a holistic approach is yet to be given priority in the industry. This paper presents an overview of POE; it presents a broad introduction, levels of investigation, POE methods, performance elements related to the housing context, and POE tools and frameworks. It also highlights key benefits to be derived from a POE and barriers forestalling its adoption in the industry. The goal of this paper is to provide a foundation and source of reference for current research in housing evaluation studies. [ABSTRACT FROM AUTHOR]

Building's energy and water consumption and associated utility costs can be significantly reduced if proper energy and water-efficiency upgrades are applied. Due to the limitations of the upgrade budgets and the availability of a wide range of energy and water-efficiency measures, decision makers are always faced with a challenging task to identify optimal sets of building upgrade measures. This paper presents the development of a new model that is capable of identifying an optimum selection of building upgrade measures to minimize equivalent annual cost (EAC) while maintaining the performance of existing buildings and complying with available upgrade budgets. The model is developed in three main phases: (1) formulation phase, where decision variables, objective function, and constraints are identified and formulated; (2) implementation phase that performs the model computations and specifies the model input and output data; and (3) performance evaluation phase where two case studies of university buildings are analyzed to demonstrate the capabilities of the model. Furthermore, a case study from the literature is used to verify the model performance and document its new capabilities. The primary contributions that this research adds to the body of knowledge are: (1) developing new model that can identify optimal selection of building upgrades while complying with user-specified requirements for building operational performance and available upgrade budgets in short computation time, (2) modeling a wide range of upgrade measures for building fixtures and equipment as well as envelope components, and (3) integrating updatable databases from vendors and suppliers to generate up-to-date and practical recommendations. The model is designed to use OpenStudio to analyze combinations of feasible alternatives such as HVAC systems, wall and roof insulations, window types, and water heaters to calculate the corresponding building energy consumption. The model is designed to perform its computations using binary linear programming to identify global optimum solutions in short computational time. The results of the case studies illustrated the capabilities of the model in optimizing building upgrade measures to reduce the building utility costs up to 38% while complying with specified upgrade budgets. [ABSTRACT FROM AUTHOR]

The influence of occupants on the dynamic properties of structures is not totally understood and can lead to overdesign, extreme vibrations, or even the collapse of buildings, stadiums, and other structures subjected to the action of standing large crowds. Several numerical models have been proposed to represent the effects of people on the structure, showing that there is not yet a consensus between the different approaches. Most of the models use masses, springs, and dampers to model the human in a standing position. Arguably, the human model could be more complex. The motor system of the human body is a complex interaction of systems (musculoskeletal, nervous, proprioceptive, etc.), all responding at distinct levels of excitation, a phenomenon that is difficult to model with a spring-mass-damper (SMD) system. This paper proposes the use of a closed-loop controller system to model the interaction of a standing human on a structure. The model is updated in a probabilistic sense using experimental data collected in a laboratory setting. The probabilistic approach allows exploration of dependencies between parameters, as well as a probabilistic estimation of the model parameters. The proposed model obtained is validated by predicting the dynamic characteristics of the combined human–structure interaction system after the mass of the structure has been modified. The closed loop controller model is able to predict the dynamic behavior of the human–structure system for a specific individual more closely than traditional SMD models found in the literature. [ABSTRACT FROM AUTHOR]

This paper presents a new stochastic methodology for evaluating and quantifying the downtime of a structure in terms of a family of fragilities that represent the probability of exceeding prescribed times to return to functionality. This methodology integrates several existing concepts, namely, Federal Emergency Management Agency P-58 and Resilience-based Earthquake Design Initiative (REDi), to build a family of system (building) level fragility curves corresponding to the time needed to achieve different recovery levels (reoccupancy, functional recovery, and full recovery). This approach enables one to propagate uncertainty throughout the procedure so that variations in the delay time and repair schedules are accounted for in the resulting fragilities. As an illustrative example of this approach, the methodology is applied to assess the downtime of a two-story mass timber building that was originally tested at the NHERI@UCSD outdoor shake table in 2017. One unique aspect of this analysis is that it incorporates a relatively new material, cross-laminated timber (CLT), in a resilient posttension rocking wall design application. Nonstructural components representing a typical office building were selected and incorporated into the procedure for the two-story CLT rocking wall building. Time-to-functionality fragility curves are then developed for the two-story building, and potential design and resilience-focused applications are discussed. [ABSTRACT FROM AUTHOR]

Oversimplifying structural modeling in the analysis of the seismic performance of tall buildings introduces variability and biases in the computed seismic response. Engineering demand parameters (EDPs) from coupled soil–structure interaction (SSI) systems can only be realistically determined when nonlinear constitutive soil and structural behaviors are adopted in the numerical formulation. Large-magnitude earthquakes mobilize soil and structural demands that are beyond the elastic response of both materials. This paper aims at evaluating the influence of the structural modeling assumptions in the computed soil response due to seismic excitations using a direct fully coupled nonlinear SSI approach. Numerical analyses are conducted on elastic and nonlinear inelastic-degrading tall building models supported on a mat foundation-to-soil continuum domain using a multiple-yield surface plane-strain constitutive model. The models were subjected to multiple ground motion scenarios representative of broadband frequency content. Large discrepancies occur between linear and nonlinear inelastic tall buildings in terms of interstory drifts, peak horizontal accelerations, structural displacements, hysteretic energy, foundation rotation, and soil settlements. The results show how using nonlinear inelastic-degrading structural models of tall buildings largely affect the computed seismic response of the entire SSI system relative to linear elastic structural modeling approaches. More realistic responses are obtained using nonlinear degrading building models including SSI effects, because energy distribution and tradeoff among both the supporting soils and structure vary significantly as the seismic demands induce stresses and strains in the building beyond the onset of structural yielding. [ABSTRACT FROM AUTHOR]

Buildings can be poorly maintained because of lack of understanding about the role of building maintenance in achieving the organization's objective and long-term profitability. The maintenance management is the agent that provides maintenance services to fulfill the needs of the organization. However, involvement of all of the key participants is the key to enhance maintenance planning, execution, and outcome whereby the participative mechanism involves the key participants dealing with the maintenance issues. Thus, this paper seeks to identify the participative mechanisms through a literature review. Then, a relationship between the mechanisms and maintenance performance through a questionnaire survey and interview is established. Finally, a regression model for prediction purposes is produced. The findings reveal that effective communication among the key participants is vital to enhance the maintenance performance. Therefore, this paper recommends that management should develop an effective communication platform involving all key participants, with contribution and commitment toward the maintenance activities. [ABSTRACT FROM AUTHOR]

Designers often cite uncertain occupant behavior as a potential obstacle to high performing buildings. However, little research has been done to characterize the nature and extent of the potential impact of the occupant on energy consumption. Energy models typically assume deterministic loads and schedules to represent occupancy and provide singular estimates of energy consumption. This paper investigates uncertainties introduced by occupant behavior by exploring the impacts of high and low comparisons on the energy performance of buildings through parametric simulation of commercial and residential buildings in two climates. The results suggest that variant occupant behavior can impact annual energy usage on the order of magnitude of 75% in residential buildings (peak load varying by 65%) and 150% for commercial buildings (peak load varying by 140%), with modest variations across climates. Although further and more sophisticated experiments are necessary, the contributions of this paper include a simple process model for assessing, through simulation, the role of the occupant on energy consumption and demonstration data about the type and magnitude of impacts that occupants can have in residential and commercial buildings across climates. [ABSTRACT FROM AUTHOR]

The authors' curve indicates URM chimneys are much more rugged than those using the Maison and McDonald curves. The discussers understand that the authors assumed all chimneys on homes built before 1970 behaved as URM chimneys (10,000 of 17,923 or 56% of inventory). We congratulate the authors for their study of plain masonry chimneys [also known as unreinforced masonry (URM) chimneys]. This underscores the challenges when calibrating models to performance observations, as both the number of damaged chimneys as well as the inventory of URM chimneys require careful estimates. [Extracted from the article]

Pinnacles on top of tall buildings are vulnerable to vortex-induced vibrations (VIVs). These structures may undergo large-amplitude vibrations that can lead to fatigue damage accumulation. To assess the performance of buildings and its appendages, numerous structural health monitoring (SHM) programs have been installed on tall buildings. This continuous monitoring generates more than 1 trillion data points per year per building. Also, on many occasions, the data generated by SHM programs contain missing observations. The evaluation of fatigue life using conventional methods becomes an impossible task in this case. This paper introduces the use of machine-learning techniques as a potential solution to deal with the burgeoning data generated by tall building monitoring systems. In particular, the present study involves the evaluation of the crosswind fatigue life of the pinnacle of Burj Khalifa subject to VIVs using cluster analysis. This unsupervised machine-learning technique is used to develop a generalized framework robust to missing data to effectively identify and extract VIVs from a large pool of other responses recorded by the monitoring system. The data generated from 2010 to 2014 by the SmartSync monitoring system installed on Burj Khalifa are utilized for this study. The proposed framework is validated using a wind tunnel dataset of a bridge sectional model undergoing VIVs. The VIVs extracted from the SmartSync system through cluster analysis are used to evaluate the crosswind fatigue damage of the pinnacle of Burj Khalifa using conventional closed-form approximations. The proposed cluster analysis framework uses a step-by-step data-driven decision-making approach, thus widening the applicability of the method to other SHM programs. [ABSTRACT FROM AUTHOR]

This paper outlines the damage observed in seven world heritage sites within the Kathmandu Valley because of the Gorkha seismic sequence of April-May 2015. Field reconnaissance was performed twice after the main shock of moment magnitude (MW) 7.8 on April 25 and after the strongest aftershock (MW 7.3) on May 12. In this paper, structural damages were classified and forensic interpretation of structural performance during four major earthquakes since 1934 is presented. A new damage function is defined for the heritages, which could affect the structural performance. Causes of damage are discussed on the basis of geology, terrain characteristics, and structural deficiencies of assessed structures. Four types of heritages were identified: pagoda, Shikhara, dome and Greco-Roman. The dome was found to be the most resilient, followed by pagoda and Shikhara, and Greco-Roman heritages were identified as the most vulnerable structures. Along with the damage report, lessons learned in terms of damage and survival of heritage structures are disseminated in this paper. [ABSTRACT FROM AUTHOR]

This paper addresses maintenance planning in heritage buildings. Currently, social, economic, and environmental factors raise concerns about the durability and service life of buildings. This study on the service life of historical buildings in terms of functionality presents a complex analysis that has yet to be developed in great depth. In this sense, a new expert system based on fuzzy logic for the prognosis of the functional service life of buildings is established. The system developed intends to manage vulnerabilities and risk variables that affect a building's performance. These parameters are involved in the building management and maintenance process and indicate durability in terms of serviceability as an output model parameter. The aim of this paper is to describe a new application of a fuzzy inference system based on expert knowledge. This approach discusses the serviceability of architectural heritage buildings using a Mamdani fuzzy model. In this methodology, the vulnerability and risk condition of nine theoretical case studies and five real buildings located in southern Spain are analyzed. In this case study, the application model is shown in a set of a five heritage buildings situated in southern Europe (Andalusia, Spain), which were only analyzed through in situ visual inspections. This system is able to give priorities relating to preventive conservation activities in homogeneous groups of heritage buildings. The approach gives useful information based on a functional criterion regarding the current state of the buildings. The fuzzy model aims to be an indicator for the future evolution of a building's functionality. [ABSTRACT FROM AUTHOR]

This paper presents a holistic postoccupancy evaluation (POE) framework and its application to a campus residential facility. The development of a framework was based on an extensive review of literature and an identification of a comprehensive set of performance indicators. Multiple evaluation techniques were employed, including the review of existing documents, interviews, walkthroughs, questionnaire surveys, and spot measurements. The importance-satisfaction (IS) matrix was utilized to identify building performance successes and failures. The study shows that occupants are moderately satisfied with their residential environment. Specific issues identified were related to HVAC and lighting systems, among others. The holistic POE framework will help to derive more qualitative feedback in housing evaluation studies for more reliable decision making. This study bridges the research gap for the need for more holistic forms of POE in the facilities management sector. The recommendations provided in this paper will serve as feedback and feedforward for the building and construction industry. [ABSTRACT FROM AUTHOR]

This paper presents the integral lifting and seismic isolation retrofit of the great hall of Nanjing Museum, a 78-year-old cultural and historical building. Due to the need for extension, the great hall of the Nanjing Museum needed to be lifted . The total building area for lifting was , with a total of 161 lifting points, which made this project quite challenging and also the largest done to date. Moreover, seismic isolation retrofit was utilized to improve the seismic performance of the translocated building. Details of the integral lifting and the seismic retrofit are presented in this paper, which include (1) the load underpinning system, (2) the spatial strengthening truss system, (3) the lifting control system, and (4) the base isolation using laminated rubber isolators. The entire lifting system performed well, and the main construction was finished within 5 months. Seismic time-history analyses were further performed to evaluate the effect of the seismic isolation. It was observed that the seismic responses of the museum were significantly reduced after retrofit. [ABSTRACT FROM AUTHOR]

This paper discusses a framework for integrated augmented reality (AR) architecture for indoor thermal performance data visualization that utilizes a mobile robot to generate environment maps. It consists of three modules: robot mapping, computational fluid dynamics (CFD) simulation, and AR visualization. The robot mapping module enables the modeling of spatial geometry using a mobile robot. In order to generate steady approximations to scanned three-dimensional data sets, the paper presents a novel “split-and-merge expectation-maximization patch fitting” (SMEMPF) planar approximation method. It allows for precise adjustment of patches independent from the initial model. The final result is a set of patches identifying planar macrostructures that consist of a collection of supported tiles. These patches are used to model the spatial geometry under investigation. The CFD simulation module facilitates the prediction of building performance databased on the spatial data generated using the SMEMPF method. The AR visualization module assists in interactive and immersive visualization of CFD simulation results. Such an integrated AR architecture will facilitate rapid multiroom mobile AR visualizations. [ABSTRACT FROM AUTHOR]

Functional recovery is a new, nonstandardized building design objective, intended to improve a building's capacity to maintain or rapidly restore basic intended functions after a natural hazard event. Current building seismic design standards, which target life-safety performance objectives, provide limited requirements to ensure buildings maintain, or rapidly recover, function after earthquakes. Therefore, the expected functional recovery performance that is provided by current building codes is unclear. To provide clear and systematic insights to inform the development of prescriptive and performance-based design standards, this study documents the functional recovery performance for a set of 60 reinforced concrete archetype buildings. The results indicate that the estimated functional recovery time for reinforced concrete buildings designed to life-safety standards may approach 1 year, on average, for design-level earthquakes. Additionally, while increased strength and stiffness requirements significantly reduce the likelihood of a building being marked as unsafe due to structural damage, additional design provisions for nonstructural components are required to ensure a high confidence of rapid recovery. The findings from this study clarify the expected post-earthquake recovery of modern reinforced concrete buildings and identify key trends in underlying damage and response mechanisms required to improve future building performance. [ABSTRACT FROM AUTHOR]

Design for wind-induced response is one of the critical factors for the design of tall buildings. Aerodynamic treatments such as corner modifications are among the traditional passive solutions for the reduction of wind-induced effects. Another practical solution is the permission of inelastic behavior under extreme wind load to reduce the resonant component of wind load. This approach has received more attention recently in performance-based wind design (PBWD) as an alternative approach for wind design. Moreover, inelastic wind design using a proper wind load reduction factor can significantly facilitate the initial design and makes PBWD more practical. In this study, the efficiency of aerodynamic modification and permission of inelastic behavior in the reduction of wind load and material cost was compared in detail. Three case study buildings with a square-shaped plan and 160 m height were considered, where one building has sharp corners and the others have chamfered and recessed corners as aerodynamic treatment. RC core walls with perimeter moment frames were considered as the structural system of all buildings, and they were designed based on wind load reduction factors of 1 (elastic design) and 2 (inelastic design). Then, the performance of buildings was evaluated according to ASCE prestandard procedure by performing linear and nonlinear time-history analysis using wind load obtained from wind tunnel tests. The results showed that inelastic wind design can be more effective than corner modification in the reduction of wind load; however, the design reinforcement ratio is less and more similar due to minimum requirement. Performance assessment of the building confirmed the adequacy of designed buildings and showed that the inelastic system has acceptable behavior, and there is a large margin of safety against failure for the inelastic building. [ABSTRACT FROM AUTHOR]

Quick and reliable identification of energy performance problems in buildings is a critical step in improving their efficiency. The current practice of building diagnostics typically involves nonintrusive data collection using thermal cameras. This requires large amounts of unordered and nongeo-tagged two-dimensional (2D) imagery to be manually analyzed at a later stage, which makes the analysis time-consuming and labor-intensive. Because of the absence of a benchmark for energy performance, identification of performance problems also heavily relies on the auditor's knowledge, and consequently may lead to subjective and error-prone inspections. As a step towards rapid and objective identification of performance problems, this paper presents a new method for automated analysis and visualization of deviations between buildings' actual and simulated energy performances. The proposed method is based on the recently developed energy performance augmented reality (EPAR) environments. In the EPAR modeling method, actual and expected three-dimensional (3D) spatio-thermal models are generated and superimposed in a common 3D virtual environment. The method leverages unordered collections of thermal and digital imagery for actual energy performance modeling, in addition to computational fluid dynamics (CFD) analysis for expected energy performance simulation. Based on the EPAR models which store actual and simulated thermal values at the level of 3D points, two new algorithms are developed to facilitate identification of potential performance problems: (1) 3D thermal mesh modeling using trees and nearest-neighbor searching to automate calculation of temperature deviations, and (2) automated visualization of performance deviations using a metaphor based on traffic light colors. The proposed modeling method is validated on several interior locations of instructional and residential buildings. Empirical observations show that automated analysis using EPAR models enables performance deviations to be rapidly and accurately measured. The visualization of deviations in three dimensions enables auditors to easily identify potential performance problems and, in turn, enables auditors to focus more on other important tasks of analyzing retrofit alternatives. [ABSTRACT FROM AUTHOR]

In this paper, the impact action of a flood on rural mountain buildings is systematically studied. First, based on the one-dimensional Saint-Venant water equation explicit-difference scheme, a new explicit-difference scheme is deduced to establish the evolutionary routing model of a flood. A computational formula about the impact loading of the flood model is deduced. Secondly, an impact experiment of a flood on buildings is carried out in a large wave-current tank. The heights of the water are 0.6, 0.9, and 1.2 m, and the distances between the building and floodgate are 3, 6, and 9 m, respectively. The model scale of the buildings is 1:6, and three buildings with different ratios of holes are designed to simulate the buildings in countries and villages. Based on the experimental results, the effects of the heights of the water, the distances between buildings and floodgates, and the ratios of holes on the impacting pressure are investigated. The numerical results are compared with the experimental results, and the distribution of impact loading is also studied. Finally, the rural building is analyzed numerically to investigate the destruction of the building because of the flood impact. The rural building is dissected into 7,950 eight-node block elements and 4,098 Goodman elements to simulate the brick and mortar, respectively. The stress, the displacement, and the failure process of the rural buildings are studied. [ABSTRACT FROM AUTHOR]

Taquezal is a common earthen building type in Nicaragua. It is constructed by building a wood frame and then packing the frame with mud to create thick earthen walls. The wood frame allows the structure to be constructed without the formwork (which is required for rammed earth buildings) and without first constructing blocks (which is generally required in adobe construction). The wood frame also allows a thinner wall than other earthen building types. Commonly, taquezal roofs are made of timber framing and heavy clay tile roofs. Taquezal buildings are not engineered and therefore are difficult to analyze with modern structural engineering methods. During the 1972 Managua earthquake, nearly 10,000 people died, and most of them were in taquezal buildings. This paper discusses taquezal as a structural system and applies engineering methods to this nonengineered structure. It was found that taquezal buildings perform well during low-to-moderate earthquakes if well maintained. However, if the wood is not maintained and allowed to rot, this degrades the roof diaphragm and wall supports, and the performance is considerably diminished. [ABSTRACT FROM AUTHOR]

Formed from a thick layer of polystyrene foam sandwiched between two layers of oriented strand board, structural insulated panels (SIPs) are a viable alternative to traditional wood stud shear walls. Developed in North America, SIPs satisfy building performance criteria while being both sustainable and cost effective. This paper details a comprehensive experimental and parametric study at Napier University examining the structural performance of shear walls constructed of SIPs under the action of both racking loads and combined bending and axial compression. The effects of size and position of openings, for doors and windows, were examined and compared to designs carried out in accordance with BS 5268 and Eurocode 5. The study has demonstrated that SIPs perform as an effective composite material possessing the strength and stiffness necessary to sustain required design loads. [ABSTRACT FROM AUTHOR]

Computational tools for early architectural design need to address issues related to building performance and integrally consider early design decisions regarding building form, spatial layout, orientation, and envelope articulation. This paper presents (1) a design optimization tool, Multiobjective Architectural Design Explorer (MADE) that supports performative-based building design, and (2) a design exploration strategy that effectively operationalizes MADE for Pareto-based comparative search. MADE implements genetic optimization in two steps. It first generates building layouts that satisfy formal, topological, and placement constraints with a single-objective genetic algorithm. Then, MADE determines the opening sizes of the generated layout(s) by optimizing the buildings' energy and daylighting performance with a multiobjective genetic algorithm.MADE is tested on the design of a library building and the proposed Pareto-based exploration strategy is demonstrated in the selection of an optimal design. The results point out the feasibility of the presented tool and the design strategy, and that multiple objectives can be satisfied by sequentially optimizing design objectives. [ABSTRACT FROM AUTHOR]

This paper investigates the response of tilt-up (referred to as "big-box") buildings subjected to two extreme hazards to which they have been observed to be susceptible--high winds (tornadoes) and earthquakes--through a performance assessment methodology utilizing fragility analysis. The methodology focuses on load characterization, defining performance goals and corresponding limit states, and assessing performance through fragility analysis. Performance goals and limit states accounting for the performance of big-box buildings during past tornado and earthquake events in the United States are identified, as are research findings reported in the literature. The proposed methodology is applied to a set of four big-box buildings representative of the current building stock in the United States, i.e., building archetypes. The building archetypes incorporate concrete tilt-up wall panels and in-plane flexible roof diaphragms that vary in size, plan aspect ratios, and roof diaphragm connectors. The results of this study show that the building size (footprint) significantly affects the performance of big-box buildings subjected to tornado wind loads but the roof connector variability does not influence the building response, given that the roof joists failed before the roof decks connections. In contrast, the performance of big-box buildings subjected to earthquake loading is highly associated with the roof diaphragm connectors used in the design phase, which are the main source of inelasticity in the roof system. [ABSTRACT FROM AUTHOR]

Despite isolated efforts in the cost assessment of design strategies for energy-efficient and resilient buildings, there is still a need for an integrated assessment that incorporates major expected costs over the entire lifecycle of the building for more comprehensive costbenefit analysis. The main goal of this paper is to broaden the scope of cost-effectiveness estimates for residential buildings by analyzing the expected costs of damage due to natural hazards in the context of other lifecycle costs. Specifically, the lifecycle cost analysis presented here includes the expected cost of repair due to earthquake and hurricane hazards as well as the energy consumption, in addition to the initial construction, routine maintenance, and home improvement. A case study is presented for a single-family, wood-frame residential building at two levels of hazard-resistant design. The overall expected lifecycle cost is estimated in terms of decision-relevant economic measures. The application of the approach to the case study under different scenarios produces some interesting insights about the sensitivity of the comparative cost analysis to different scenarios regarding the locations, future values, and economic measure of comparison. [ABSTRACT FROM AUTHOR]

A limited amount of data exists on the cyclic behavior of concrete-filled steel deck diaphragms, and the few historical testing programs that have been conducted used specimens that may not be representative of modern floor assemblies typical in North America. As part of a larger research project, the Steel Diaphragm Innovation Initiative, an experimental program was conducted to fill critical knowledge gaps related to the behavior and design of concrete-filled steel deck diaphragms leading to a better understanding of the seismic performance of steel buildings utilizing these types of diaphragms. The experimental program included eight diaphragm specimens that were approximately 4 m by 5 m, tested in a cantilever test setup wherein one edge is restrained against translation while the opposing edge is subjected to an in-plane cyclic displacement history. Parameters that were varied included deck height (51 mm and 76 mm), concrete cover over the deck (51 mm to 115 mm), concrete type (normal weight and lightweight), configuration of perimeter headed shear studs, and the presence and amount of reinforcing steel. Specimen behavior was quantified including initial stiffness, peak shear strength, ductility, and energy dissipation and qualitatively connected to observed cracking and deformations. The results of this experimental program, combined with tests from the literature were used to develop proposed expressions for peak shear strength and initial stiffness. The proposed expressions reasonably capture the experimental results and are suitable for design. [ABSTRACT FROM AUTHOR]

This paper addresses field investigations of the performance of masonry buildings during the October 23 (Erciş) and November 9 (Edremit), 2011, Van earthquakes in Turkey. Erciş and Edremit are villages respectively located 90 km and 18 km from the city of Van in Turkey. Ground accelerations and response spectra for these earthquakes are discussed. A total of 28,000 buildings were damaged or collapsed in the city center and surrounding villages after the Erciş earthquake. This number increased to 35,000 after the Edremit earthquake. Almost all masonry buildings were affected in the region. Most of them in the area were constructed of random or coursed stone walls with no reinforcement to support heavy clay tile roofing over wooden logs. A large number of such buildings were heavily damaged or collapsed. Cracking and failure patterns are examined and interpreted according to current provisions for earthquake resistance of masonry structures. From the field investigations, it is shown that damages had several causes, among them site effect, location and length of the fault, and poor construction quality. In addition, the two earthquakes hit the masonry buildings within 17 days, causing progressive damage. A large number of nonengineered masonry buildings completely collapsed or were heavily damaged. Most of those in the affected area were not designed and constructed in accordance with the Turkish Earthquake Resistant Design Code. [ABSTRACT FROM AUTHOR]

This paper presents a method to facilitate the assessment of the performance and analyze the degradation of building envelopes, focusing on painted finishes. The proposed solution consists of systematizing the inspections, diagnosis, and rehabilitation methods through the compilation and structuring of the data contained in current regulations and scientific publications which are later validated and adjusted by the statistical analysis of data gathered in an inspection's campaign. The field campaign included a sample of 105 façades with painted renders in the city of Lisbon, Portugal. The scope of the sample was limited to painted rendered façades (cementitious or mixed-binder mortar), therefore excluding other substrates. As a result, terminology, techniques, and procedures are combined into a single innovative system that allows unequivocal decision-making regarding inspections and intervention on paint coatings, thereby minimizing reliance on the experience of the inspector. The system is composed of several tools including classification lists, correlation matrices, and individual files compiling information on pathologies, testing, and repair techniques. The method for application of these tools is also described in this paper. [ABSTRACT FROM AUTHOR]

Commercial buildings, which are ubiquitous in metropolises, are typically equipped with a wide range of facilities. Satisfactory operation of the facilities necessitates provision of effective maintenance works in the long run. Since, fully computerized maintenance management systems are seldom adopted for facilities in commercial buildings, the dearth of proper maintenance data makes it difficult to investigate their maintenance performance. Reported in this paper is an examination of the maintenance data of a large commercial building, which were recorded semi-automatically by a computer-aided maintenance system. The maintenance works were found to be mainly corrective in nature, dominated by the electrical trade. Existing occupancy and business operation were influential to the issue time of the work orders. Benchmarks of response time, repair time, and downtime were established for evaluation and benchmarking purposes. Further works are needed to probe into the factors that affect maintenance performance, especially the effectiveness of maintenance manpower deployment. [ABSTRACT FROM AUTHOR]

Support bearings have a very important role in the structural performance of bridges. As an integral part of the bridge, bearings must guarantee a service life that is compatible with that of the remaining bridge components. However, the service life of support bearings is often lower than that of the bridge, leading to repair or replacement operations, which can be relatively expensive and may cause considerable inconvenience to the traffic flow. This paper follows a recent study performed by the authors, in which an inspection and diagnosis system for road bridge structural bearings was proposed. It presents the application of the system to a sample of 152 support bearings in Portuguese road bridges, which is also deemed representative of bridge bearings in most European countries. The results obtained allowed performing a statistical analysis in which a number of aspects were evaluated, namely, the characteristics of the bearings, the anomalies, their causes and degree of urgency of intervention, the inspection and diagnosis methods, and the most appropriate maintenance and rehabilitation techniques. The results obtained allow characterizing and understanding in further depth the behavior of these bridge components, providing a number of lessons on bridge bearing design, execution, and maintenance. [ABSTRACT FROM AUTHOR]

High voltage porcelain bushings mounted on transformers have shown vulnerability during past earthquakes. This is contrary to the generally good performance observed during shake table qualification testing of bushings anchored to a rigid base. The seismic vulnerability of porcelain bushings might be caused by the flexibility of transformer tanks and of bushing attachments. Current seismic qualification guidelines consider an amplification factor of 2.0 between the amplitude of the ground motion and the amplitude of the motion at the base of the bushing. This paper investigates numerically the dynamic response of porcelain bushings mounted on transformer tanks. The results of the numerical study show that large amplification occurs when the fundamental frequency of the porcelain bushing is tuned with the fundamental frequency of the transformer tank. [ABSTRACT FROM AUTHOR]

This paper presents a multicriteria optimization method for the performance-based seismic design of steel building frameworks under (equivalent static) seismic loading. Minimizing structural cost (interpreted as structural weight) is taken as one objective. The other objective concerns minimizing earthquake damage which, since uniform postelastic ductility demand over all stories generally avoids local weak-story collapse, is interpreted as providing a uniform interstory drift distribution over the height of the building. That is, the overall objective for the design of a building framework is to have minimum structural weight and uniform plastic ductility demand while, at the same time, meeting displacement and strength constraints corresponding to the various performance levels. Explicit forms of the objective functions and constraints in terms of member sizing variables are formulated to enable computer solution for the optimization model. The concepts are illustrated for three-story and nine-story steel building frame examples. [ABSTRACT FROM AUTHOR]

Part II. Looks at the role of inherent randomness and modeling uncertainty on building performance, using the nonlinear dynamic analysis procedure. Estimation of the structural response and damage in steel frames; Damage measures and limit states; Factorial analysis of parameters in degraded connection model; Stochastic response analysis of buildings; Seismic fragility model; Conclusions and recommendations.

The damage caused by seismic shaking and liquefaction-induced permanent ground deformation has conventionally been assessed as two separate problems often by different engineers. However, the two problems are inherently linked, since ground shaking causes liquefaction, and liquefaction-induced soil softening affects ground shaking. Modelling both problems within a single numerical model is complex for both the engineer and the software, and most finite element software only have the capabilities to address one of them. To improve the estimates of the seismic performance of buildings on liquefiable soil, a new sub-structuring approach is proposed called the macro-mechanism approach. This approach allows the soil-liquefaction-foundation-structure interaction to be considered in a series of sub-models accounting for the major nonlinear mechanisms of the system at a macro level. The proposed approach was implemented in the open-source finite element software OpenSees and then applied to a case study of a building where significant liquefaction- and shaking-induced damage was observed after the 1999 Mw 7.4 Kocaeli Earthquake. The case study building was also simulated using two different commercial software programs, the finite difference software FLAC, and the finite element software PLAXIS, by two different research teams. A comparison between the results from the macro-mechanism approach compared to full numerical models shows that the macro-mechanism approach can capture the extent of the foundation deformation and provide more realistic estimates of the building damage than full approaches since the FLAC and PLAXIS models consider elastic elements for the building. [ABSTRACT FROM AUTHOR]

Nonlinear response history analyses were conducted to determine the seismic collapse safety and seismic performance of buildings with special steel moment frames using Simpson Strong-Tie Strong-Frame moment frames compared to equivalent buildings using reduced beam section (RBS) moment frames. The Strong-Frame moment connection consists of a modified T-stub or end plate connection incorporating Yield-Link structural fuses for moment transfer, and a modified shear plate connection for shear transfer. Archetypical 4-story, 8-story, 12-story, and 20-story steel frame buildings designed using ASCE 7-16 were evaluated. The results indicate that the Strong-Frame buildings have a 36% larger adjusted collapse margin ratio and are less likely to collapse, compared to the RBS buildings. The Strong-Frame buildings also have lower probable repair costs and shorter repair time compared to the RBS buildings. The improved collapse safety and enhanced performance of the Strong-Frame buildings are attributed to the stronger column web panel zone, inclusion of column bending moments in seismic overstrength load combinations, delayed connection strength degradation, a distributed global collapse mechanism, and replaceable connection components. [ABSTRACT FROM AUTHOR]

Flexible civil structures are prone to aerodynamic instabilities, such as long-span bridges and high-rise buildings, and wind-induced vibration is harmful to structural life-span and users' comfort. To address this issue, this study proposes a new aerodynamic countermeasure that is designed to improve the structural aerodynamic performance, i.e., adding a strip seam cover device (SSCD) on the surface of a structure, and the influence of the device on the aerostatic performance of the main structure is presented. Taking the box girder of long-span bridges, for example, the effectiveness and influence factors of the proposed device are investigated in detail. First, the proposed device is introduced and three aerostatic force coefficients are selected as the evaluation indices for the SSCD's effectiveness. Second, the typical streamlined box-girder sectional model of bridges with and without the additional device is compared respectively based on the two-dimensional (2D) computational fluid dynamics (CFD) simulation technique. Results show the bridge girder's pitch moment coefficients can be decreased efficiently. In addition, influences of gap distance (i.e., 30 cm, 60 cm, 90 cm, and 120 cm) between the device and the bridge girder, effective width (i.e., 50 cm, 60 cm, 90 cm, and 180 cm), and void ratio (i.e., 1∶5 , 1∶3 , 1∶2 , 1∶1 , 2∶1 , and 5∶1) of seams are investigated based on wind tunnel tests. Results of the same cases based on the experiment and CFD simulation are very close, showing the accuracy of the simulation and experiment. Experimental results show that the gap distance is recommended to be 60 to 90 cm, the effective width is 90 cm, and the void ratio is recommended to be a value larger than 1∶1. In this case, the pitch moment value and the slope of the curve for the pitch moment coefficient versus wind attack angle are efficiently reduced, which is beneficial for improving the critical wind speed of aerostatic torsional divergence and aerostatic stability. The proposed device can be used to improve the aerostatic and aerodynamic performances of buildings, bridges, and some other structures; moreover, its potential application in the control of vortex-induced vibration is found preliminarily, which will be reported in further study. [ABSTRACT FROM AUTHOR]

Current tall building design to ultimate wind loads is based on a linear elastic design framework. The adoption of a performance-based wind design framework for tall buildings explicitly requires evaluation of building performance under various levels of wind hazards, including inelastic response. This study presents a comprehensive characterization of inelastic response of tall buildings under simultaneous actions of both alongwind and crosswind loads using a fiber-based three-dimensional (3D) nonlinear finite-element (FE) model of a 60-story high-rise steel building. The statistics of inelastic responses in terms of building displacement, acceleration, interstory drift, and base bending moment and member forces are quantified through response history analysis at different wind speeds. The inelastic building responses under alongwind and crosswind loads acting separately are also calculated and compared. The inelastic response is also compared to the elastic response of the corresponding linear building model. The yielding causes building drift in the alongwind direction that leads to increasing time-varying mean displacement. The development of drift is affected by fluctuating alongwind and crosswind responses. The steady-state value of drift is determined by the mean load and second stiffness in the alongwind direction. On the other hand, the fluctuating alongwind and crosswind responses can be quantified regardless of the mean load and time-varying mean response. The yielding leads to a reduction of fluctuating responses due to additional hysteretic damping. The second-order P-Delta effect on both elastic and inelastic responses is also examined. Finally, the influence of material yield stress is investigated, and the inelastic response is discussed in nondimensional quantities. The results of this study reveal the importance of consideration of simultaneous actions of both alongwind and crosswind loads for inelastic response analysis. The inelastic crosswind response affects the alongwind inelastic response. It particularly results in increased time-varying mean alongwind displacement, which contributes to building collapse when the second-order P-Delta effect is considered. [ABSTRACT FROM AUTHOR]

A new pushover analysis procedure derived through adaptive modal combinations (AMC) is proposed for evaluating the seismic performance of building structures. The methodology offers a direct multimode technique to estimate seismic demands and attempts to integrate concepts built into the capacity spectrum method recommended in ATC-40 (1996), the adaptive method originally proposed by Gupta and Kunnath (2000) and the modal pushover analysis advocated by Chopra and Goel (2002). The AMC procedure accounts for higher mode effects by combining the response of individual modal pushover analyses and incorporates the effects of varying dynamic characteristics during the inelastic response via its adaptive feature. The applied lateral forces used in the progressive pushover analysis are based on instantaneous inertia force distributions across the height of the building for each mode. A novel feature of the procedure is that the target displacement is estimated and updated dynamically during the analysis by incorporating energy-based modal capacity curves in conjunction with constant-ductility capacity spectra. Hence it eliminates the need to approximate the target displacement prior to commencing the pushover analysis. The methodology is applied to two existing steel moment-frame buildings and it is demonstrated that the AMC procedure can reasonably estimate critical demand parameters such as roof displacement and interstory drift for both far-fault and near-fault records, and consequently provides a reliable tool for performance assessment of building structures. [ABSTRACT FROM AUTHOR]

Providing an air cavity behind vinyl siding within a building envelope is an approach to mitigating building moisture-related issues, which also improves the building's thermal performance. Previous studies commonly assume the cavity air as still and thus neglect the influence of mixed convection on the performance of the building envelope. Additionally, the air cavity is usually considered uniformly rectangular, neglecting the effects of its geometric irregularity and complexity. Therefore, to comprehensively investigate the effects of air cavities, this study analyzes ratios of siding depth to cavity depth in the mixed convection of air cavities, through rigorously formulating the problem and solving it using the perturbation method. The results show that increasing the ratio of the vinyl siding depth to the air cavity depth amplifies the metrics directly related to the energy performance of the building envelope, including the cavity air's velocity, temperature, and mass fraction; the skin friction at cavity walls; as well as heat and mass transfer across the cavity. The effects of other critical parameters are also investigated, including the Reynolds number and temperature of the irregular cavity wall. This study provides guidance for comprehensively evaluating the thermal performance of an air cavity behind vinyl siding and improving the design of vinyl siding. [ABSTRACT FROM AUTHOR]

A case study was conducted on 44 residential homes using both traditional house wrap and ZIP System systems to measure the overall airtightness and compare estimated energy usages. The labor, material, and overhead and profit (O&P) costs were analyzed and used to determine the optimal choice for long-term benefits in terms of cost and performance. The impact of insulation installation is considered a key factor in improving the strategy of reducing energy consumption. Improved installation practices can affect the airtightness of common wall assemblies to reduce the building energy performance gaps and provide insight on how to allocate resources better. A framework was developed to analyze operational costs and building energy performance to address how installation quality is a factor in the return of investment in building construction for heating and cooling systems within the thermal envelope. With this methodology, aggressive energy performance goals will be met while balancing the tradeoff between installation techniques and building systems efficiency based on the introduced probabilistic investment return (PIR) metric. [ABSTRACT FROM AUTHOR]