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A new cable-damper stopper equipped for Coal-Fired Thermal Power Plants (CFTPPs) was proposed in our previous paper, where a series of shaking table tests were carried out to investigate its seismic performance, so this paper aims to reveal the working mechanism of the stopper from the theoretical and numerical simulation aspects. The stopper is composed of three main components, i.e. a steel cable, a steel block and a viscous damper. First, the nonlinear restraint stiffness of the steel cable to the boiler was derived; second, the critical damping of the stopper, which makes the vibration of the boiler decay exponentially with no oscillation, was derived; third, an iterative method was proposed to globally tune the CFTPP structure, which makes it possible to obtain the optimal parameters of the cable-damper stopper, including the diameter of the steel cable and damping coefficient of the damper. Finally, finite element models were built and time history analyses were conducted to verify the proposed optimization approach. Firstly, the finite element models were proved valid through the comparison between the results of the simulations and the experiments. Then, based on the results of the simulations, the theoretical procedure was validated. The results revealed that the proposed cable-damper stopper reduced the seismic responses of displacements of the top floor and the boiler significantly, about 30.18% and 60.01% respectively compared with their counterparts of CFTPPs without stoppers. [ABSTRACT FROM AUTHOR]

This paper proposes probabilistic demand models to assess fragilities for high-rise buildings with three types of outrigger systems under seismic and wind loads. Parameters of the structural model are determined based on the structural material and geometric conditions. Parameters of the excitation model are determined based on the hazard characterization that varies with the hazard type. This paper involves three types of hazards: high-frequency ground motions, near-fault ground motions, and stochastic wind loads. With the input information from the structural model and the excitation model, 3D finite element models are built and computed using ANSYS to obtain structural responses (output information). Based on a database with the input-output pair obtained, we formulate probabilistic demand models for high-rise buildings with three types of outrigger systems under three types of hazards. These probabilistic models are proposed to estimate three response quantities of interest, the maximum inter-story drift, the maximum top acceleration, and the maximum top displacement. They, therefore, include univariate, bivariate, and tri-variate models. The probabilistic demand models account for both aleatory and epistemic uncertainties and provide unbiased estimates. With a direct and parsimonious formula, they have high accuracy and are extremely convenient to be used in practical engineering. They are finally used to formulate fragility estimates with bounds for an example high-rise building with three types of outrigger systems under three types of hazards. The results indicate that damped outrigger systems can effectively reduce fragilities for high-rise buildings under three types of hazards. [ABSTRACT FROM AUTHOR]

Axial forces are generated in the plates of ADAS-yielding dampers when subjected to lateral loading due to their boundary conditions. This on one hand can lead to an increase in strain level of the plates and accelerate the damage process, while on the other hand, the interaction of the bending moment with the tensile axial force leads to increasing strength, which is undesirable in the performance of ductile members. In this paper, a modified ADAS device (MADAS) is introduced to prevent undesirable interaction of axial forces, and its cyclic behavior is evaluated both experimentally and numerically. To this end, in the first step, two test specimens with different number of connection pins were prepared and subjected to cyclic loading in a rigid frame. Experimental and numerical results have shown that due to the removal of the constraint in the vertical direction, the level of forces produced by the damper is almost constant and the X-shaped plates have been able to tolerate significant number of cycles before crack initiation. Afterwards, the cyclic performance of ADAS and MADAS dampers was numerically compared individually and also when placed in the frame. Furthermore, in the frame equipped with ADAS damper, the increase in the level of forces produced by the damper led to the buckling of the braces, while the level of generated forces was totally in the expected range in the frame equipped with MADAS damper. [ABSTRACT FROM AUTHOR]

Earthquake-induced pounding in bridges is a complex contact phenomenon in which the dynamic responses of structures, including collisions between deck and abutments, are strongly related to structural properties and earthquake excitation. The goal of this study is to develop and compare the seismic fragility curves of overall system and individual components of regular and irregular box-girder highway bridges in two cases: with pounding and without pounding. For this purpose, four levels of altitudinal irregularity, ranging from regular to highly irregular, are considered. To extend the results for all bridges in the same class, different sources of uncertainties related to earthquakes, structural geometries, and material properties are taken into account. The analytical fragility curves have been developed based on nonlinear time history analyses in OpenSees finite element software for the cases with and without pounding effects. The process has been repeated for each two-, three-, and four-span classes at four irregularity levels. The fragility function parameters for the two cases with and without pounding have been compared for all classes considered in this study. Using fragility functions, this paper clarifies the interactive roles of irregularity and pounding between deck and abutments for seismic vulnerability of multi-span box-birder highway bridges. The results indicate that collisions often show an adverse effect on all structural components. It has also been observed that the detrimental effect of pounding on seismic fragility is more apparent in irregular bridges when compared with regular ones. In addition, the study introduces a conversion coefficient to clarify the effects of pounding on the fragility of bridge components and the overall system. This coefficient can be applied in both conventional analytical methods like static or simplified analysis and technical earthquake models like HAZUS, adjusting fragility values for pounding and irregularity effects. [ABSTRACT FROM AUTHOR]

The paper investigates the stiffness and strength of log walls with standard and dovetail bonded corners under lateral loads. The finite element model is developed and validated with experimental work at small-scale and wall-scale levels. The validated wall-scale model was modified by conducting a detailed investigation on assessing the wall behaviour with varying crucial parameters, including coefficient of friction, vertical load, geometric irregularities, and the wall's aspect ratio. The study suggested various techniques for improving the wall's lateral load resistance capacities and initial stiffness, employing steel and wood pins. [ABSTRACT FROM AUTHOR]

The fragility and capacity of historical structures can be evaluated under seismic loads with the help of a rigid-base assumption by neglecting soil–structure interaction effects. However, this approach may not be accurate because earthquake waves reach the structure by spreading through a soil medium. Wave propagation, soil amplification, and deformability of the subsoil may affect the seismic response of structures. Therefore, soil–structure interaction should be considered in the finite element model, especially in historical structures that require detailed analyses to determine the structural behavior. This paper focuses on the structural behavior of the Santa Maria Church and its Guesthouse Building, which are two of the historical landmarks in Trabzon, Turkey. The church, which has features that distinguish it from similar structures belonging to its period, is one of the important symbols for the city of Trabzon and continues its religious function. The seismic performance of the building was evaluated based on the soil – structure interactions for different soil conditions. The finite element models of the buildings were generated based on earthquake input models (rigid-base free earthquake input, massless-soil-free earthquake input, massed-soil-free earthquake input, and massed-soil deconvolved earthquake input models) and different soil conditions (hard, medium, and soft soil). Time-history analyses were conducted based on earthquake input models (rigid-base free earthquake input, massless-soil-free earthquake input, massed-soil-free earthquake input, and massed-soil deconvolved earthquake input models) and different soil conditions (hard, medium, and soft soil). Time-history analyses were conducted with respect to the horizontal components of the 1992 Erzincan Earthquake. Evaluating the effects of earthquake input models on the seismic responses was done with respect to the obtained maximum displacement and principal stress. The results show that the soil–structure interaction and the soil types have significantly altered the structural responses of both buildings. [ABSTRACT FROM AUTHOR]

Precast structures are widely used in Southern Europe particularly for industrial buildings. Most of such buildings have been built before the enforcement of modern anti-seismic regulations showing a poor performance during past major earthquakes. Focusing on existing one-storey precast industrial buildings, the paper investigates the influence of modelling choices on the risk assessment, direct losses, and required structure retrofit time. RC forks, cladding panels, and elements connections were specifically considered. A precast industrial building with structural details compatible with 1980s Italian regulations was selected and analysed. In general, the failure was associated with the collapse of roof elements. [ABSTRACT FROM AUTHOR]

Most previous research on seismic performance of cross-laminated timber (CLT) structures focused on platform-type construction. This paper investigates the seismic performance and collapse risk of a balloon-framed CLT school building, designed for Vancouver, Canada. Incremental dynamic analysis was performed using a three-dimensional numerical model. Experimental data from connection- and wall-level tests were used to calibrate and validate the model. Twenty-one ground motions (crustal, subduction inslab, and interface) were selected. The results showed the building well met the 2% design drift limit. It had 4.2% probability of collapse at design level by considering uncertainties with a collapse margin ratio of 3.18. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of multi-components strong motion duration on seismic performance of high concrete-faced rockfill dams (CFRDs) by fragility analysis based on the method of incremental dynamic analysis (IDA). The contributions of all compositions of earthquake excitations are considered by the definition of integrated duration based on the concept of significant duration. The nonlinear finite element model of a 2D 200-m-high CFRD is established as a case study and the vertical and horizontal displacements are selected as damage measures. Fragility curves and probabilities of two sets of 23 and 25 spectrally equivalent as-recorded bi-directional long-duration and short-duration motions are determined under different failure grades and intensities. The results show that the duration of vertical component has a certain effect on correction between strong motion duration and deformation of the dam and fragility analysis indicates that the ground motions with long duration can make more risk of failure of high CFRDs than short duration motions. Therefore, the seismic performance of high CFRDs will be reformed by taking the effect of ground motion duration into seismic design and risk assessment consideration. [ABSTRACT FROM AUTHOR]

Safety assessment of vehicles crossing highway interchanges during earthquakes by reliability-based numerical simulations is presented in this paper. The assessment was performed for two limit states: vehicle rollover and sideslipping accidents. Simulations were conducted using three-dimensional finite element models of two existing highway interchanges consisting of straight and curved bridges under site-specific earthquakes. Effects of curved bridges radii, levels of earthquake, vehicle type, driving velocity, and road surface conditions on the safety limit states of five types of vehicles, namely, sedan-type, SUV, small-box truck, bus, and large truck, were investigated and clarified in the Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

Nonlinear finite-element model updating (FEMU) is a promising approach for post-event damage assessment of civil structures. This paper conducted FEMU for a full-scale reinforced concrete bridge column tested under a sequence of earthquakes and examined the evolution of seismic damage across different earthquake ground motions. It was found that using experimental data, FEMU can be applied to identify unknown key model parameters (e.g. bond-slip and core concrete parameters) and damage of the columns as represented by the change of the key parameters. In addition, the updated models demonstrated their ability to better predict the system response for future earthquakes. [ABSTRACT FROM AUTHOR]

This paper proposes a novel semi-rigid rocking wall-floor connection. To study its seismic behavior, a preliminary study using finite element modeling (FEM) has been conducted to perceive the rocking wall response towards the precast plank before conducting a physical experimental testing in the laboratory. The finite element model was developed to investigate the lateral quasi-static-load response of the isolated rocking wall system. Subsequently, the rocking wall model was further extended by incorporating a precast concrete plank using the proposed connection. The finite element model of the rocking wall showed a good correlation with the analytical model. Furthermore, the study showed that a semi-rigid connection would result in an overstrength that should be considered when designing the rocking wall. [ABSTRACT FROM AUTHOR]

A resilient rocking steel column base (RRSCB) installed with composite combination disc spring (CCDS) is proposed in this paper. The restoring force model and energy calculation formulae of the RRSCB are derived by the theoretical analyses and energy conservation law, respectively. A refined finite element model validated by the cyclic loading tests is established with the aid of ABAQUS to investigate the seismic performance of the RRSCB. The results indicate that the RRSCB possesses satisfactory self-centering capability and desirable energy dissipation capacity for the design displacement. The established restoring force model and energy calculation formulae can reasonably predict the hysteretic behavior of RRSCB under cyclic loading. [ABSTRACT FROM AUTHOR]

The residual displacement of column has significant effect on the post-earthquake functionality of bridge. In this paper, the nonlinear finite element model of a simply supported beam bridge was built. The seismic performance of reinforced concrete column, unbonded prestressed reinforced concrete (UBPRC) column, and fully prestressed column was compared. Quasi-static residual displacement was adopted in the fragility analysis. The result showed that the quasi-static residual displacement affects the vulnerability of bridge system only for the collapse damage limit state. UBPRC column is a good balance between the vulnerability arising from peak displacement and residual displacement. [ABSTRACT FROM AUTHOR]

In this paper, a comparative study between the smeared crack and extended finite element method (XFEM) is performed. Also, the effective parameters for predicting crack profiles are investigated. The results show that the crack profile in the two models is partially different. Also, the important difference between the two models is computational efficiency. In addition to analysis time, complexity algorithm of XFEM is noticeable. Update assembling matrices, determine interaction integral and control of crack mouth opening at each loading step require enough space of memory which with increasing number of elements, ordinary computers run out of memory during solving. [ABSTRACT FROM AUTHOR]

This paper presents a seismic pounding risk-based method to determine the minimum separation distance (MSD) between nonlinear adjacent buildings. In this method, subset simulation is extended to assess seismic pounding fragility and subsequent risk. The MSD is iteratively solved corresponding to a target pounding risk. First, the proposed method is applied to both linear and nonlinear multi-degree-of-freedom systems with substantially different dynamic properties for various structural parameters. Then, the MSDs between three combinations of adjacent frame structures with unequal total heights in nonlinear finite element models are investigated using the proposed method, which are compared with different code specifications. [ABSTRACT FROM AUTHOR]

This paper analyses the influence of friction coefficient and equivalent radius on the seismic reduction effect of friction pendulum bearings in the underground station under far-field and near-field earthquakes with different strength. It is found that the parameters of the friction pendulum bearings will obviously influence seismic reduction effectiveness. By combining genetic algorithm with finite element method, the parameters of friction pendulum bearings in the station can be optimized. By using this method, the optimal parameters range can be obtained, which can provide reference for parameter design of friction pendulum bearings in underground stations. [ABSTRACT FROM AUTHOR]

The dynamic behaviour of dry stone monuments is highly nonlinear as it involves rocking and slippage of numerous blocks, and occasionally cracking of blocks and plastic deformation of metal connectors. This is why the assessment of the efficiency of structural interventions (for restoration purposes) on such monuments located in seismic areas is a very complicated task. One way to address this issue is nonlinear dynamic numerical analysis in which material nonlinearity is taken into account for each component of the structure (blocks, connectors). This paper advocates that this is the way by which the most accurate results are to be expected, provided that all models are sufficiently validated. With this aim, such a holistic numerical approach is presented, regarding the assessment of the seismic performance of new titanium connectors designed for the architrave of an ancient-Greek temple, currently under restoration. The monument is the temple of Apollo Epikourios at Bassai, Peloponnese, which is included in the UNESCO World Heritage List since 1986. The numerical analyses, in overall, showed a way of using a sophisticated FE software for the design or the evaluation of one of the most common structural interventions on dry stone monuments (the replacement of the ancient connectors of the stone blocks with new elements made of titanium), as well as they demonstrated the key benefits of this use (global overview, detailed analysis, and easiness in conducting parametric investigations). Furthermore, they yielded quantitative information concerning the efficiency of a major intervention on an important ancient temple. [ABSTRACT FROM AUTHOR]

This paper proposes a novel earthquake-resilient steel joint with a replaceable buckling-restrained link (RBRL). To study its seismic behavior and post-earthquake resilience performance, five full-scale specimens are tested under cyclic loads, during which three parameters are investigated: the web connection type, the connecting plate thickness and the core plate stiffeners. The experimental results are presented in terms of the test phenomena, hysteresis curves (corresponding skeleton curves, energy dissipation capacity parameters and stiffness degradation curves), and the displacements and strains at key positions. The test results show that the proposed joint can achieve the expected replaceable and hysteresis performance, the joint with welded web connections is prone to welding tear failures, and the connecting plate thickness and the stiffeners have an insubstantial influence on the performance. Finally, finite element models are built and validated through comparisons with the test results. [ABSTRACT FROM AUTHOR]

This paper aims to study the combined effects of incident wave angularity and geometrical characteristics on the seismic spectral response of curved valleys filled with alluvium. The parametric studies were carried out using a numerical tool, called HYBRID, which combines the Finite Element Method (FEM) and Boundary Element Method (BEM) to model the near field and far field, respectively. Some criteria were provided considering the coupled effects of wave incident angles, and topographical and geometrical characteristics on the seismic site response. This will help engineers in assessing the soil-structure interaction problems in alluvial valleys. [ABSTRACT FROM AUTHOR]

This paper describes techniques for detecting bearing malfunction directly from the seismic response of the bridge using wavelet transform time-varying identification. Instantaneous frequency of continuous wavelet and detail components of discrete wavelet transform are utilized as structural features, and they characterize isolation bearing condition via statistical clustering technique. Accuracy and efficacy of the techniques were verified in numerical simulations using analytical and finite element models. The techniques were implemented on seismic records from long-term monitoring of multi-span continuous-girder isolated bridge. Results demonstrate that wavelet-based features can effectively characterize the condition of the isolation bearing directly from seismic responses of girder and piers. [ABSTRACT FROM AUTHOR]

This paper investigates the seismic bearing capacity of strip footings on undrained clay with single continuous square voids. Numerical studies for a wide range of geometric parameters and material properties are performed using adaptive finite element limit analysis (AFELA). Based on the pseudo-static approach, rigorous upper and lower bounds of the seismic bearing capacity for the strip footing are obtained, with relative errors of 4% or better. The calculated results are presented in the form of design tables and charts, and the effects of different governing parameters on the seismic bearing capacity are evaluated, including the size and location of the voids, the dimensionless strength ratio and the horizontal seismic coefficient. In addition, typical failure mechanisms are examined, and comparisons with previous studies are also conducted. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic response of multi-drum columns using the finite element method. Properly derived 3-D models based on a scaled replica of an ancient marble column are used in the simulations. The model properties are carefully selected to reduce analysis time without sacrificing the accuracy of the results. The dynamic behavior of the system under random and earthquake excitations is examined. A parametric analysis for crucial modeling quantities is performed, comparing numerical results with experimental measurements. A reasonable prediction of the response of multi-drum columns can be obtained for a carefully selected, suitable choice of the model parameters. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the influences of steel diagonal braces (SDB) on the deformation performance and seismic behavior of steel truss-RC tubular column hybrid structures. Firstly, the vertical deformation performance of the structures with and without SDB was compared through finite element analysis. Then, pseudo-dynamic tests were carried out to investigate the seismic behavior of a 1/8-scaled substructure with SDB, and hysteretic curves were obtained by applying a subsequent displacement-controlled cyclic loading. The test results indicated that adding SDB is an effective approach to decrease the deflections of steel truss and enables to improve the lateral stiffness and lateral bearing capacity of the steel truss-RC tubular column hybrid structure. In addition, numerical modeling of the specimen with SDB was built on the basis of the refined finite element program. The comparisons between the finite element analysis and test results indicated that the FE modeling approach is reasonable to predict the seismic behavior of this type of hybrid structure. [ABSTRACT FROM AUTHOR]