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It has been found that in the event of a strong earthquake, and due to insufficient distance between two adjacent structures, the lateral movement at the top of structures may cause collisions between them. This phenomenon, commonly known as seismic collision, can generate impact forces that were not considered during the initial design of the structure. These forces can cause significant structural damage or lead to complete collapse of the structure. The main purpose of this paper is to study the coupled effects of soil flexibility and impact between adjacent buildings undergoing seismic excitation. To capture the impact forces between the structures during the collision, a modified linear viscoelastic model was used effectively. Particular attention has been paid to studying the effects of shear wave velocity, first on the soil structure interaction and then on the collision response of adjacent structures. Three configurations of adjacent structures were analyzed: light-light, light-heavy, and heavy-heavy structures. The results obtained through this analysis showed that the dynamic response and the impact force of the structures depend essentially on the interaction between the structure, the foundation, and the soil. [ABSTRACT FROM AUTHOR]

Interference effects of two adjacent foundations include changing failure mechanism, load settlement, and stress distribution behavior; this can result damages such as differential settlement, tilting, cracking, reduction of serviceability, and even failure. To address these issues, the present study aims to assess the effect of the number of new adjacent building stories on settlement and the tilt of the existing building. The study evaluates the interference effects of two adjacent foundations on sand and fill by finite-element Plaxis 3D in two groups. The first numerical modeling group is conducted in a small scale and compared with laboratory tests that are performed on a 1 g chamber with a height and diameter of 1 m, thickness of 0.01 m, revealing a similar settlement and tilting pattern. The second group is modeled two closely circular footings in full scale. The results showed that the induced settlement increases as the number of stories increases, from 7.5 to 23.5 mm for sand and 25.6 to 38.2 mm for fill, respectively, when the applied load increases from 40 to 100 kN/m2. Moreover, in the fill soil, the settlement of the foundation's center was, on average, 167% more than that of sand, with an increase in the number of stories from 4 to 6, and this difference reduced to about 77% in higher stories. Finally, three real cases include "Guilan Residential Building, Grain Silos and Athens Buildings" are evaluated by numerical modeling and induced complications assessed. [ABSTRACT FROM AUTHOR]

Controlling the deformation of the pit and adjacent building in the excavation process is the key factor in the design of deep foundation excavation work. Due to the high support capacity, the support structure consisting of a diaphragm wall and isolation pile is commonly utilized in such projects. Based on a deep foundation pit project for a metro station in Nanning, Guangxi, the current study investigates the partial parameters of isolation piles in the combined support structure. In this context, the effect of different positions of the isolation pile bottom on the settlement of the soil around the pit, the deformation of the building and the pit, and other laws, by varying the length of the isolation pile and its horizontal distance to the enclosure structure, is investigated. The findings show that the position of the base of the isolation pile relative to the sliding surface of the soil is the main factor affecting the soil settlement, the moment distribution in the enclosure structure, and the building deformation when other parameters of the isolation pile remain constant. In this article, a formula is developed to determine the insertion depth, and a design method is presented to determine the optimum length of the isolation pile based on available relevant research, after summarising the series of laws. [ABSTRACT FROM AUTHOR]

This paper proposes a novel seismic demand hazard model conditional on the separation distance between two adjacent buildings to fully explore the possibility of seismic pounding occurrence between buildings during their design life. The model uses an exponential function with two model parameters estimated through a two-point approach to yield an explicit expression for deriving a Seismic Demand Hazard Curve (SDHC) for adjacent buildings. The resulting SDHC provides a basis for seismic pounding risk assessment of adjacent buildings with a specific separation distance and a design tool for the risk-targeted separation distance between buildings. To verify the model, this paper compares the SDHCs derived for six pairs of adjacent buildings having different heights and natural period combinations with corresponding numerical simulation results. The results show that the SDHCs derived from the model, within the engineering interest range, closely agree with numerical simulation results. [ABSTRACT FROM AUTHOR]

In order to improve the seismic performance of adjacent buildings, two types of tuned inerter damper (TID) damping systems for adjacent buildings are proposed, which are composed of springs, inerter devices and dampers in serial or in parallel. The dynamic equations of TID adjacent building damping systems were derived, and the H2 norm criterion was used to optimize and adjust them, so that the system had the optimum damping performance under white noise random excitation. Taking TID frequency ratio and damping ratio as optimization parameters, the optimum analytical solutions of the displacement frequency response of the undamped structure under white noise excitation were obtained. The results showed that compared with the classic TMD, TID could obtain a better damping effect in the adjacent buildings. Comparing the TIDs composed of serial or parallel, it was found that the parallel TIDs had more significant advantages in controlling the peak displacement frequency response, while the H2 norm of the displacement frequency response of the damping system under the coupling of serial TID was smaller. Taking the adjacent building composed of two ten-story frame structures as an example, the displacement and energy collection time history analysis of the adjacent building coupled with the optimum design parameter TIDs were carried out. It was found that TID had a better damping effect in the full-time range compared with the classic TMD. This paper also studied the potential power of TID in adjacent buildings, which can be converted into available power resources during earthquakes. [ABSTRACT FROM AUTHOR]

The excavation of the foundation pit will have an impact on the adjacent buildings and the presence of the buildings will increase the risk of the construction of the pit. It is important to carry out studies on the interaction between the excavation and the adjacent buildings. Taking the Wenhua Road deep excavation project in Shenyang as the background, the influence of excavation on the displacement of the enclosure pile was analyzed through on-site monitoring data, and then a three-dimensional numerical model was established and compared with the on-site monitoring data to verify the accuracy of the model. Finally, the interaction behavior between the deep excavation and the building was analyzed under the parameters of the stiffness of the enclosure pile, the number of storeys of the building and the relative position of the deep excavation and the building. The results show that the use of retaining piles combined with anchor cable support will significantly reduce the deformation of retaining piles caused by excavation. The settlement and horizontal displacement of the building foundation caused by the excavation are within 5% with the increase in the stiffness of the bollard piles. The settlement and horizontal displacement of the building foundations increase by approximately 8% and 10% respectively for each additional 5 storeys of the building, and the horizontal displacement of the foundation piles near the building increases by approximately 5. 5% . At an angle of 30° or more between the building and the excavation, the deformation of the building foundation caused by the pit excavation was within 2 mm, and the horizontal displacement of the encasement piles was within 0. 8 mm. The results can be used as a reference for similar projects in the future. [ABSTRACT FROM AUTHOR]

Grouting is often used for active real-time control of deformation of adjacent important buildings and structures caused by excavation. However, when the distance between grouting and excavation is small, grouting may pose a threat to the excavation support system. At present, there is no effective way to solve that. Taking the excavation of a super deep subway station foundation pit was unalyzed adjacent to a hospital sensitive building in Tianjin as an example, the impact of the excavation of the foundation pit was analyzed and restores the building settlement by grouting in the soil layer between the super deep subway station and the hospital sensitive building. Because the vertical grouting has a great adverse effect on the excavation supporting structure, the inclined grouting is proposed in this paper to reduce the impact on the excavation. The results show that the adverse effect of inclined grouting on the adjacent station excavation is significantly reduced compared with vertical grouting, while the control of building settlement is still effective. When the angle of inclined grouting is too large to reduce the settlement of one side of the building adjacent to the grouting body, large upheavals will occur at other locations; Increasing the buried depth of the top of the grouting body can weaken the building uplift phenomenon and make the building settlement recover more evenly. [ABSTRACT FROM AUTHOR]

It has been found that in the event of a strong earthquake, and due to insufficient distance between two adjacent structures, the lateral movement at the top of structures may cause collisions between them. This phenomenon, commonly known as seismic collision, can generate impact forces that were not considered during the initial design of the structure. These forces can cause significant structural damage or lead to complete collapse of the structure. The main purpose of this paper is to study the coupled effects of soil flexibility and impact between adjacent buildings undergoing seismic excitation. To capture the impact forces between the structures during the collision, a modified linear viscoelastic model was used effectively. Particular attention has been paid to studying the effects of shear wave velocity, first on the soil structure interaction and then on the collision response of adjacent structures. Three configurations of adjacent structures were analyzed: light-light, light-heavy, and heavy-heavy structures. The results obtained through this analysis showed that the dynamic response and the impact force of the structures depend essentially on the interaction between the structure, the foundation, and the soil.

Preservation of historic buildings is a main challenge in the civil engineering field. One of the main concerns about this subject is to be sure of environmental effects like noise and vibration on monuments. To overcome these problems, a wide range of noise and vibration mitigation measures could be applied. To reach a proper evaluation, in this paper, a detailed assessment is made on the efficiency of various vibration mitigation measures by a series of field tests and sensitivity analysis in Isfahan metro lines close to some vibration-sensitive cultural structures. The sensitivity analysis was performed in possible ranges of vertical stiffness of track superstructure materials. Results showed that vertical track stiffness equal to 5 kn/mm would lead to a 5 db reduction with regarding 4 millimeters limit of rail deflection. [ABSTRACT FROM AUTHOR]

Pounding between adjacent buildings subjected to ground motion excitation is one of the most dangerous phenomena for building safety. In this paper, three novel configurations are proposed (two of them are uncoupled, and one of them is coupled), and two different passive devices are used, namely, tuned mass damper inerter (TMDI) and tuned inerter damper (TID). In addition, the proposed configurations are investigated for pounding mitigation. To determine the devices' optimum parameters (mass, inertance, stiffness, and damping), a particle swarm optimization algorithm is used. The objective function is set to minimize the peak of the frequency response functions of interstory drift. The proposed configurations are compared with the best existing configuration in the literature. A large set of ground motion records is used to illustrate the efficiency of the proposed configurations. Based on the results, it is found that the proposed uncoupled configurations by using TMDIs or TIDs perform better than the existing configuration in the literature. [ABSTRACT FROM AUTHOR]

The topic of pounding of adjacent structures has greatly attracted the attention of researchers in recent years. Among the observed damages due to the earthquake, one could refer to those damages induced by pounding of the adjacent structures which is a prevalent phenomenon. The reason for this issue is the lack of separation joint or its inadequacy between two adjacent buildings. When an earthquake occurs, difference in the structures' frequencies would result in difference in their reaction relative to the ground acceleration and pounding would take place. In this article the effects of site soil type, structure type, its height and distance from the fault on the separation joint for the steel and reinforced concrete moment resisting buildings with 3, 5, 8 and 12 stories are investigated. The structural models are first designed by structural design software and then are analyzed under various time histories using Seismostruct software. The obtained results show that the highest hazard risks corresponding to collision between the adjacent buildings belong to areas near the faults located on soft soil types and collision of two buildings with different types is the most severe collision. Different conditions have been discussed in this paper and based on the results, some editions to criteria of seismic design code of Iran has been proposed considering to distance to active faults, soil conditions and type of structure.

When constructing a retaining wall adjacent to existing basements, the width of the soil mass can be limited. The traditional theories are not suitable for calculating the earth pressure for limited width of soil. Moreover, research achievements and engineering practice in recent years have indicated that most types of soil follow a nonlinear failure criteria. For overcoming such issues, based on a nonlinear failure criterion, an analytical formula was derived in this study by using infinitesimal method; and according to the soil arching theory, the ratio Kawn was introduced to define the ratio of horizontal to vertical stress. Through discussion and case studies, the optimum value of the ratio Kawn was obtained and numerical results showed that this method is feasible for the calculation of active earth pressure for limited width of soil. Finally, the effects of the parameters in the nonlinear failure criterion on active earth pressure were further studied, and results showed the significant effects of the parameters of the height of retaining wall H, unit weight γ, n (n = δt/φt), surcharge q0, the primary cohesion c0, axial tensile stress σt and the length between the retaining wall and the wall of existing basement L on active earth pressure. [ABSTRACT FROM AUTHOR]

Control of adjacent structures during an earthquake is one of the major challenges in engineering practices. Connecting two structures with the use of a damper is considered to be one of the effective vibration control and reducing damage approaches. Improving the seismic performance of weak structures by connecting them to substructures is an effective method. The type of dampers and the characteristics of input earthquake loading play an important role in the performance of connected buildings. In addition, some previous studies have shown that viscous dampers, besides the problem of sensitivity to temperature and oil leakage, could not be much effective against near-fault records. In this study, the vibration control of smaller frequency structures while connected to robust structures with two types of dampers (i.e., friction and yielding) was investigated Three distinctive sets of earthquake records were considered to be the excitation input data. To this end, three 3-, 5-, and 8-story buildings were selected and the effects of applying friction and yielding dampers to control their vibration while subjected to the abovementioned records were studied. The results imply that both dampers performed well when subjected to near-fault records; however, the performance varies depending on the type of earthquake. A maximum displacement reduction rate of 64% was observed. Friction and yielding dampers have shown more effective performance in the middle and at the top stories, respectively. As the number of stories increased, the effectiveness of lower stories dampers to reduce seismic responses decreased, so their application could be neglected. [ABSTRACT FROM AUTHOR]

Summary: The use of supplemental damping for mitigation of seismic hazard of adjacent building structures is proven to be a practical and efficient way. In developing an efficient damper/energy absorber, shape memory alloy (SMA) material is an excellent candidate due to its well‐known high‐energy dissipation capacity via thermomechanical‐phase transformation. For the first time, the present study focuses on the seismic response control efficiency of superelasticity SMA damper over conventional yield damper, for vibration control of adjacent building structures. To this end, the response of two adjacent steel building frame structures connected with SMA and yield dampers is evaluated through nonlinear dynamic time‐history analysis, under a set of recorded near‐fault ground motions. Optimal characteristics of both dampers are obtained through a parametric study. The robustness of the improved performance of the SMA damper over the yield damper is studied for various characteristic damper strengths, building structures, as well as different scenarios of seismic loading. It is being demonstrated that the superelasticity SMA damper significantly improves the floor displacement control efficiency over the yield damper and also provides a considerable amount of reduction in the peak value of the absolute floor acceleration. [ABSTRACT FROM AUTHOR]

Nowadays, the use of control systems in buildings has been increased and the importance of vibration reduction of structures is considered more than ever. In addition to improve the dynamic behavior of buildings, control systems can be installed between adjacent buildings as activated, semi-active and inactivated systems. Fluid viscous dampers are one of the most important approaches for inactivated control systems in which the dynamic response of two adjacent buildings reduces according to the high resistance of the viscous fluid. The main purpose of this study is the use of control systems in two similar adjacent buildings to reduce the entire system response which will be the analytical study of the impact of viscous dampers to control system performance. In order to provide the analysis and to study the dynamic behavior improvement of different adjacent buildings connected with dampers, two models of the original sample was investigated. All examples are different from each other and response analysis and time history was provided using SAP 2000 software. According to the acquired results, the effect of fluid viscous dampers for tall buildings is less than the shorter ones. Moreover, these dampers are more efficiently working for adjacent buildings with different heights rather than buildings with the same height.

For better assessing the monitoring risk of adjacent buildings in the excavating environment, a novel model based on fuzzy cloud model (FCM) was developed. FCM is an organic integration of fuzzy theory (FT) and cloud model (CM), where FT is used to flexibly describe a quantitative process from complete attachment to the counter and CM is appropriately employed to eliminate the uncertainty of fuzziness and randomness during the gradation of evaluation factors. Firstly, a risk evaluation system is established by taking risk indicators as identification factors. Secondly, analytic hierarchy process (AHP) is utilized to calculate the weight of risk indicators, and FCM is applied for cloud computing of experts' comments, with both the subjectivity of experts' comments and the uncertainty of assessment indicators fully considered. Finally, the correlation between the calculated cloud results of each risk index and the risk standard cloud model is obtained to evaluate the integrated risk grade of adjacent buildings in the excavating environment. In addition, the results of the application using FCM in the foundation pit of Yue Bei Yuan (YBY) match well with the actual engineering situation. At the same time, three types of monitoring risks of YBY are discussed for further verifying the superiority of the evaluation method FCM. The results suggest that the model for monitoring risk of adjacent buildings in excavating environment is efficient and accurate. Moreover, the internal risks prove to be most significant. [ABSTRACT FROM AUTHOR]

The embedded ratio of retaining structures and improved depth of ground at an excavation base are two key factors for the stability of deep excavation. For a collapsed excavation in soft clay in Hangzhou, China, a numerical investigation using the finite-element method (FEM) is carried out on the buildings distressed by excessive settlement and wall deformation. The embedded ratio of retaining piles and improved depth of ground at the excavation base are thus examined for their impact on the ground settlement and wall deformation of the building caused. A dimensionless parameter–wall torsion tilt ω –is introduced to analyze the differential settlement of buildings caused by adjacent excavation. The results indicate the following: (1) the insufficient embedded depth of retaining piles is the main cause of the building instability, and (2) increasing the embedded ratio of a retaining pile or the improved depth of ground at the excavation base can effectively reduce the ground settlement induced by excavation and, thus, limit the large differential vertical deformation on the wall of an adjacent building. [ABSTRACT FROM AUTHOR]

Determining a minimum separation distance required to avoid seismic pounding between adjacent buildings is a capacity‐demand design issue. This study developed a spectral approach to evaluate the expected minimum separation demand (referred to as the critical separation distance, [CSD]) to prevent pounding between buildings during strong earthquake motions. Presented firstly in this paper is an analytical procedure for evaluating the relative displacement process at the potential pounding location between two adjacent buildings during earthquake motions. The procedure is based on random vibration theory and modal analysis with application of the well‐known CQC rule. Subsequently, an approximate nonlinear closed‐form solution for evaluating CSD is derived, by means of a simplified spectral‐based procedure with introducing the concept of equivalent linearization of nonlinear hysteretic behavior and the effective correlation coefficients of the generalized coordinates of equivalent linearized systems to consider inelastic vibration phase between buildings. Finally, the CSDs between two buildings having different heights and the same height for various combinations of buildings with different fundamental periods are separately examined as verification examples of the proposed approach. The accuracy of solution is demonstrated by comparing computed results with corresponding numerical results from nonlinear response history analyses (RHAs). The results show that the proposed approach provides a reliable solution in predicting the separation demand of buildings during earthquake motions. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the effect of collisions between the adjacent structures during the earthquake and its effect on the behavior of the structure. The collisions could lead to local damage or even total collapse of colliding structures. A model was performed on the ETABS program to model the pounding between the adjacent structures by using Gap element. The study was applied on a different height and a gap distance between the adjacent structures in order to understand and explain the effect of collision on the behavior of the structure and to clarify the danger of its occurrence. The results of the studied cases in case of pounding were compared with the normal case without pounding, where the Displacement, inter storey drift, impact force and max storey shear force were discussed. These results showed that both buildings were affected by the collision .Therefore, precautions should be taken to prevent the collision by having sufficient distance or design a system that can withstand the force resulting from these shocks.

This paper investigates the seismic design of fluid viscous dampers connecting adjacent structural systems. A simplified dampers design strategy is proposed, which relies on a linearized reduced order model of the coupled system. A stochastic linearization technique is adopted with the aim of extending the design method to non-linear viscous dampers. The effectiveness of the design method and of the coupling strategy are assessed via numerical analysis of two adjacent buildings with shear-type behavior connected by linear or non-linear viscous dampers and subjected to Gaussian stochastic base acceleration. Different dampers locations are analyzed. The accuracy of the reduced order model is assessed, by comparing the relevant response statistics to those provided by a refined multi degree of freedoms model. Finally, a parametric study is performed to assess the effectiveness of dissipative connection for different values of seismic intensity and dampers parameters (i.e., viscous coefficients and velocity exponents).

Currently, new housing in city centers is more and more often developed on small plots of land, or existing buildings on such plots are rebuilt to such an extent that only their façade walls remain. In both cases, as a rule, a deep excavation is also made, either at the existing object or within its area. Serious damage often occurs because of the carried out work. It is not possible to accurately determine the response of a building to the deformation associated with the excavation due to the variability of many factors that influence it. As a result, the response of the building must be estimated on the basis of constant monitoring and approximate calculations. Depending on the size of the predicted ground displacements and the technical condition of buildings, it is often necessary to protect or strengthen their structural elements. In the paper, the authors analyzed various risk factors for the implementation of infill buildings and the revitalization of historic buildings using only their façade walls. In addition, examples of contemporary solutions for securing the walls of existing buildings, and the method of monitoring vertical deformations using the Hydrostatic Levelling Cell (HLC) system, are presented. [ABSTRACT FROM AUTHOR]

Finding effective means of protecting structures from dynamic hazards is a challenging task and has gained increasing significance. As for the seismically excited adjacent structures, an intelligent control strategy using magnetorheological dampers as connection devices considering soil--structure interaction is presented. First, the calculation model for the coupled structure--soil--structure interaction--magnetorheological damper system is developed, and the motion equation for calculating the seismic responses is then derived. Second, a semiactive control strategy integrating a modified crow search algorithm into a fuzzy logic control is proposed. In this strategy, to accurately calculate the voltage of magnetorheological dampers, the modified crow search algorithm with a hybrid coding strategy, priority selection scheme for target crows, new solution updating method, and guarantee mechanism of the solution feasibility is proposed to design the fuzzy logic control system. The numerical example of 10-story and 20-story coupled buildings demonstrates that soil-- structure interaction should be taken into consideration to avoid overestimating the control effect. Besides, the proposed modified crow search algorithm outperforms genetic algorithm in terms of accuracy and robustness. Furthermore, by using magnetorheological dampers to interconnect the coupled structure with soil--structure interaction, dual advantages, that is response reduction and pounding mitigation can be achieved. The proposed modified crow search algorithm--fuzzy logic control method shows comprehensive performance superiority over its competitors, that is passive-off, passive-on, on--off, linear quadratic regulator--clipped voltage law, and linear quadratic Gaussian--clipped voltage law control strategies. [ABSTRACT FROM AUTHOR]

Summary: The tuned mass damper inerter (TMDI) is an enhanced variant of the tuned mass damper (TMD) that benefits from the mass‐amplification effect of the inerter. Here, a multi‐TMDI (MTMDI) system (comprising more than one TMDI) linking two adjacent high‐rise buildings is presented as an unconventional seismic protection strategy. The relative acceleration response of the adjacent structures triggers large reaction forces of the inerter devices in the MTMDI, which in turn efficiently improve the seismic performance of the two buildings. By addressing a real project of two adjacent high‐rise buildings connected by two corridors equipped with the proposed MTMDI system, the displacement‐, interstory drift‐, and acceleration‐based parametric optimizations are separately performed by employing Nondominated Sorting Genetic Algorithm II (NSGA‐II) under 44 ground motions from the FEMA P695 far‐field record set. It is found that the frequency content of the seismic input has strong impact on the MTMDI mitigation performance. Adopting realistic mass ratio constraints, the optimally designed MTMDI outperforms both conventional MTMD and single TMDI in acceleration control, while it is not much effective in mitigating the displacement response due to the highly flexible nature of the high‐rise buildings, in contrast to other literature studies generally focused on low‐to‐medium rise buildings. [ABSTRACT FROM AUTHOR]

In this article, damage assessment of adjacent 3, 5 and 7 storey fixed- and isolated-base steel building frames is evaluated under multiple ground motions. Seismic damage of adjacent buildings has been mostly investigated in previous studies, based on single earthquake by ignoring the influence of repeated earthquake phenomenon and base-condition. In this study, the Park-Ang damage index has been developed in MATLAB platform to quantify the damage level for steel moment-resisting frames. The study concludes that, under multiple ground motions, base-isolators decrease the damage index of 3, 5 and 7 storey adjacent buildings by 57%, 60% and 66%, respectively. [ABSTRACT FROM AUTHOR]

This study explores the effectiveness of shared tuned mass damper (STMD) in reducing seismic pounding of adjacent buildings. The dynamics of STMDs is explored through numerical simulations of buildings idealized as single and multiple degree of freedom oscillators. An optimization method proposed in the literature is revisited. It is shown that the optimization results in two different solutions. The first one corresponds to the device being tuned to one of the buildings it is attached to. The second solution corresponds to a very stiff system where the TMD mass hardly moves. This solution, which has been described as an STMD in the literature, is shown to be impractical due to its high stiffness and use of a heavy stationary mass that plays no role in response mitigation but adds unnecessary load to the structure. Furthermore, it is shown that the second solution is equivalent to a viscous coupling of the two buildings. As for the properly tuned solution, i.e., the first solution, sharing the device with an adjacent building was found to provide no added benefits compared to when it is placed on one of the buildings. Based on results from a large set of real earthquake ground motions, it is shown that sharing a TMD mass with an adjacent building, in contrary to what is reported in the literature, is not an effective strategy. [ABSTRACT FROM AUTHOR]

Structural pounding can lead to local or total damage to the stories at the collision level or to the overall collapse of the building. On the other hand, lateral stiffness irregularity is common in the form of soft or very soft stories, which is due to the alternation in the type of function of the first story of the building. This paper estimates the demand for the normalized separation gap (NSG) at adjacent buildings highest collision level that were a combination of regular and irregular frames. For this purpose, the steel moment resisting frames (MRF), compounds with a total of 700 adjacent states and their NSG, is calculated by the dynamic time history analysis. In addition, irregularity increment in lateral stiffness for the first story could lead to an increase in the NSG of 84% of the adjacent combinations. In this study, a new relationship is proposed to estimate the demand for the NSG with the consideration of the effects of irregularity of lateral stiffness in the lowest story. [ABSTRACT FROM AUTHOR]

• Simultaneous effects of pounding, torsion and structure-soil-structure interaction (SSSI) are studied. • SSSI increases the number of occasions and amplitude of the pounding force. • Torsional impact at the corners acts like an amplification factor for the torsional response. • The amplified torsional response makes the peripheral frames the most critical ones. • SSSI amplifies the plastic action of peripheral frames of torsional buildings to more than two times. The effects of earthquake induced pounding on the nonlinear response of torsionally coupled buildings resting on flexible soil are investigated in the current study. Three steel moment-resisting frame buildings with the same symmetric plan having 4, 7 and 10 stories are considered. Three-dimensional nonlinear models with different eccentricity ratios are created. The soil-structure interaction phenomenon is taken into account using the Winkler beam on nonlinear springs. The pair of adjacent structures spaced at different clear distances resting on a flexible soil are analyzed under a consistent set of ground motion records and the effects of seismic pounding, torsional eccentricity and soil-structure interaction are studied by comparison of nonlinear dynamic responses of buildings. The results show that the peripheral frames experienced the most critical conditions during earthquake-induced pounding and the combined effect of soil-structure interaction, torsional eccentricity and pounding results in the most severe nonlinear responses of the studied buildings in certain cases. [ABSTRACT FROM AUTHOR]

Approximately, 65% of the existing residential structures are adjacent in Turkey. In addition to the social disadvantages of living in adjacent buildings, these structures are prone to pounding during earthquakes and they are under threat during the construction and demolition of the neighboring structures. The neighboring structures may experience damage during/after the demolition of adjacent structures due to pounding of structural components. There are many cases of casualties and economic losses due to the collapse of neighboring structures during the demolition of old structures. The damage can be occurred as a result of constructing shared foundations, different foundation depths, the groundwater level, and possible impact of the work machine during demolition. Also, in areas with high seismic risk, there is a possibility of an earthquake at a time between the demolition and reconstruction stages of a building, which can cause significant damage. Due to these reasons, the design and construction stages of adjacent structures should be described by building codes in detail. In order to renew the adjacent structures at different times, horizontal support elements should be used and required design calculations should be made. This study examines the truss system applications as horizontal support in such structures built in Eskisehir. The characteristics of the section and system properties, the horizontal load carrying capacity, the choice of support zones between the adjacent structures, and the characteristics of strain deformation are determined. It is concluded that the horizontal support applications prevent horizontal forces due to earthquakes and various vibrations in neighboring structures and prevent structural deformation. • Determination of the effect of the horizontal support systems to joints or beam • Investigation of the critical buckling loads of horizontal support systems • The effect of horizontal support elements on lateral load transfer with neighboring buildings • Analyses of buildings with horizontal support systems under Düzce Earthquake acceleration records • To find the displacements in adjacent buildings with horizontal support systems [ABSTRACT FROM AUTHOR]

Summary: Expansion joints are used as a special connection equipment between adjacent buildings to accommodate the relative motions generated by wind, thermal, or earthquake loads, but they often exhibit damage during severe earthquakes. The level of damage and safety factors required to avoid loss of function are not well considered in current design practices. The objective of this paper is to provide quantitative information on the seismic damage probability of common expansion joints and the associated repair costs. The designer and engineer can refer to this information as a basis for decision making in the selection of expansion joints. Four common types of expansion joints are considered: high‐ and standard‐performance floor and wall expansion joints, whose damage states have been evaluated recently by the authors through shaking table tests. First, the fragility functions of expansion joints for seven damage patterns are developed utilizing the test results. Next, the vulnerability of expansion joints installed between adjacent building models is assessed via incremental dynamic analysis. The recommended level of safety factor to ensure the function of expansion joints is discussed. Finally, a procedure for cost‐effective selection of expansion joints is introduced, where case studies are examined using buildings with different characteristics. The presented results are deemed to be beneficial for improving the design practice of expansion joints and for reducing future seismic loss. [ABSTRACT FROM AUTHOR]

• There is an increasing demand for conducting nonlinear dynamic analysis to account for permanent deformations. • The adaptive controller deals quite well with the nonlinear behavior. • MR damper is promising control device. • Connecting adjacent buildings with MR dampers is an effective strategy. The efficacy of using the simple adaptive control method for alleviating the seismic responses of two nonlinear adjacent buildings connected at multiple levels with magneto-rheological dampers is investigated. The connected system is formed by two shear-type model buildings of the same height but have different dynamic characteristics so that the fundamental frequencies of the individual buildings do not coincide. A stable hysteretic behavior of the structural system is considered in the current study, which captures the variation in flexibility and energy loss under various intensity levels of seismic events. The Bouc-Wen's nonlinear differential equation is utilized to model the hysteretic behavior of the restoring force-displacement smooth curve of the developed nonlinear structural system which is then integrated into a semi-active adaptive control system. The advantage of using the Bouc-Wen model is that it has the ability to mathematically track various shapes of the force-displacement curves by adjusting its non-dimensional parameters. The proposed nonlinear model is validated through a finite element model. Adaptive control is well suited to handle the nonlinear behavior because the adaptive control gains can be adjusted depending on the situation through a closed-loop action to yield better performance. The results show that using the adaptive controller to drive the magneto-rheological dampers connecting two adjacent nonlinear buildings can be used to effectively alleviate the seismic responses and reduce permanent deformations. However, the performance improvement is not the same under all ground motions considered in this study. [ABSTRACT FROM AUTHOR]

Several municipal seismic vulnerability investigations have been identified pounding of adjacent structures as one of the main hazards due to the constrained separation distance between adjacent buildings. Consequently, an assessment of the seismic pounding risk of buildings is superficial in future adjustment of design code provisions for buildings. The seismic lateral oscillation of adjacent buildings with eccentric alignment is partly restrained, and therefore a torsional response demand is induced in the building under earthquake excitation due to eccentric pounding. In this paper, the influence of the eccentric seismic pounding on the design demands for adjacent symmetric buildings with eccentric alignment is presented. A mathematical simulation is formulated to evaluate the eccentric pounding effects on the seismic design demands of adjacent buildings, where the seismic response analysis of adjacent buildings in series during collisions is investigated for various design parameters that include number of stories; in-plan alignment configurations, and then compared with that for no-pounding case. According to the herein outcomes, the effects of seismic pounding severity is mainly depending on characteristics of vibrations of the adjacent buildings and on the characteristics of input ground motions as well. The position of the building wherever exterior or interior alignment also, influences the seismic pounding severity as the effect of exposed direction from one or two sides. The response of acceleration and the shear force demands appear to be greater in case of adjacent buildings as seismic pounding at different levels of stories, than that in case of no-pounding buildings. The results confirm that torsional oscillations due to eccentric pounding play a significant role in the overall pounding-involved response of symmetric buildings under earthquake excitation due to horizontal eccentric alignment. [ABSTRACT FROM AUTHOR]

Summary: The problem of the through‐soil coupling of structures has puzzled the researchers in the field for a long while, especially regarding the varied performance of identical, adjacent buildings in earthquakes. The phenomenon of structure‐soil‐structure interaction (SSSI) that has often been overlooked is recently being recognized: The possible effects in urban regions are yet to be thoroughly quantified. In this respect, the goal of this work was to rigorously investigate the interacting effects of adjacent buildings in a two‐dimensional setting. Detailed finite element models of 5‐, 15‐, and 30‐story structures, realistically designed, were used in forming building clusters on the viscoelastic half‐space. Perfectly matched layers were used to properly define the half‐space boundaries. The interaction of the structure and the soil medium because of the presence of spatially varying ground motion on the boundary of excavated region was considered. The effects of the foundation material and the distance between adjacent buildings on the structural behavior of the neighboring buildings were investigated using drift ratios and base shear quantities as the engineering demand parameters of interest. The effects of SSSI, first investigated in the frequency domain, was then quantified in the time domain using suites of appropriate ground motions in accordance with the soil conditions, and the results were compared with the counterpart SSI solution of a single building. The results showed that, for identical low‐rise structures, the effects of SSSI were negligible. Yet, neglecting SSSI for neighboring closely spaced high‐rise structures or building clusters with a large stiffness contrast was shown to lead to a considerable underestimation of the true seismic demands even compared with solutions obtained using the rigid base assumption. [ABSTRACT FROM AUTHOR]

In order to study the deformation law of adjacent building structures, surface settlement, displacement of supporting piles, axial force and variation of water level during different excavation stages of deep excavation construction, the deep foundation pit project in the M1 line of the Jinan Metro was used as the background, and the data from field measurement of excavation and support were analyzed. The results show that the horizontal displacement of the pile presented a pronounced "bow" shape with the excavation of the foundation pit. The maximum horizontal displacement of the pile appeared at one third of the top of the pile, with a maximum of 31.98 mm. The maximum value of monitored axial force was 3100 kN, which was much less than the control value of 6847 kN. The maximum axial force appeared on the second steel support. The axial force of the first reinforced concrete support rapidly increased with the time. It was considered that the initial bearing capacity of the concrete was low, so the axial force of the concrete support was smaller than the steel support. The strength and load-bearing capacity of concrete increased in the later period, which resulted in a rapid increase in axial force. At the same time, during the process of setting up or dismantling the support, the attention should be paid to the axial force change of the adjacent support to prevent the danger caused by the abrupt change of the axial force. The maximum settlement value of the building appeared at the two corners far from the foundation pit, with the value of 4.3 mm. When the constructions were 34 m away from the deep foundation pit, the impact of dewatering on the building was greater than that of the foundation pit excavation, and he effect of the dewatering on the variational soil texture in this area was different. The maximum angular variation of adjacent constructions was 1/16,050, which was less than the 1/5000 of the minimum angular variation. The foundation pit structure and building were in a safe state, and the layout of the supporting structure was reasonable. [ABSTRACT FROM AUTHOR]

One of the effective methods to reduce the seismic response of the adjacent buildings is to connect these buildings by passive dampers. In this research, the seismic performance of this type of control system is evaluated using fragility curves. Furthermore, the parameters and arrangement of the connecting viscous dampers are investigated. For this purpose, two 8- and 12-story RC special moment-resisting frame buildings are connected by viscous dampers. After obtaining the appropriate parameters and arrangement of dampers, incremental dynamic analysis was performed under 22 far-field ground motions using OpenSees software. Assuming a log-normal distribution, the probability of exceedance of the performance level is calculated at each maximum ground acceleration value as a fragility curve. The fragility curves show that the connection of adjacent buildings by viscous dampers will improve the seismic performance of both connected buildings compared to the corresponding results of single uncontrolled buildings. • The optimal seismic performance of connected buildings is achieved when the dampers are on the same floor level. • Viscous dampers reduce inter-story drift and floor levels drifts in both connected buildings by reducing maximum drift. • The study found that connecting buildings significantly improved their seismic performance, particularly in shorter buildings. [ABSTRACT FROM AUTHOR]

Currently, new housing in city centers is more and more often developed on small plots of land, or existing buildings on such plots are rebuilt to such an extent that only their façade walls remain. In both cases, as a rule, a deep excavation is also made, either at the existing object or within its area. Serious damage often occurs because of the carried out work. It is not possible to accurately determine the response of a building to the deformation associated with the excavation due to the variability of many factors that influence it. As a result, the response of the building must be estimated on the basis of constant monitoring and approximate calculations. Depending on the size of the predicted ground displacements and the technical condition of buildings, it is often necessary to protect or strengthen their structural elements. In the paper, the authors analyzed various risk factors for the implementation of infill buildings and the revitalization of historic buildings using only their façade walls. In addition, examples of contemporary solutions for securing the walls of existing buildings, and the method of monitoring vertical deformations using the Hydrostatic Levelling Cell (HLC) system, are presented.