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Ground motions and seismic site factors for the design and analysis of infrastructure systems are typically computed based on one-dimensional (1-D) site response analysis, assuming the ground surface is horizontal and the earthquake waves propagate vertically near the ground surface. The 1-D results may not be applicable for sloping ground surfaces and layer interfaces, and therefore, the 1-D results must be adjusted for sloping grounds. In this study, a general framework for developing seismic site factors for sloping grounds and its application for Charleston, SC is presented. The two-dimensional (2-D) site response analysis results of sloping ground were compared with the 1-D horizontal ground results to develop slope adjustment factors. A total of 385 2-D nonlinear finite element simulations of sloping grounds were performed considering seven ground inclinations, 11 shear wave velocity profiles, and five ground motions representative of the area. The results show that the surface responses computed from sloping ground analyses significantly differ from those of horizontal ground analyses. By comparing the 1-D and 2-D results, a set of slope adjustment factors was developed and expressed as an easy-to-use chart. The slope adjustment factor at a project site can be obtained from the proposed chart using site-specific VS30 and ground inclination at a selected period. [ABSTRACT FROM AUTHOR]

It is widely acknowledged that the effects of soil-structure interaction (SSI) can have substantial implications during periods of intense seismic activity; therefore, accurate quantification of these effects is of paramount importance in the design of earthquake-resistant structures. The analysis of SSI is typically conducted using either direct or substructure methods. Both of these approaches involve the use of numerical models with truncated or reduced-order computational domains. To ensure effective truncation, it is crucial to employ boundary representations that are capable of perfectly absorbing outgoing waves and allowing for the consistent application of input motions. At present, such capabilities are not widely available to researchers and practicing engineers. In order to address this issue, this study implemented the Domain Reduction Method (DRM) and Perfectly Matched Discrete Layers (PMDLs) in OpenSees. The accuracy and stability of these implementations were verified through the use of vertical and inclined incident SV waves in a two-dimensional problem. In terms of computational efficiency, PMDLs require a shorter analysis time (e.g., with PMDLs, the analysis concluded in 35 min as compared to 250 min with extended domain method) and less computational power (one processor for PMDLs against 20 processors for the extended domain method) thus offering a balance between accuracy and efficiency. Furthermore, illustrative examples of the aforementioned implemented features are presented, namely the response analysis of single-cell and double-cell tunnels exposed to plane waves inclined at an angle. [ABSTRACT FROM AUTHOR]

This paper quantified the seismic resilience (SR) of different bridge classes by performing three-dimensional advanced numerical simulations in Opensees. SR was calculated by performing the seismic resilience for recovery investments of bridge (SRRIB) methodology that is based on the quantification of the losses and the repair time. In particular, the probabilistic-based methodology developed by the Pacific Earthquake Engineering Research Center (PEER) was implemented to produce fragility curves by considering the longitudinal displacement of the deck as the reference parameter. The recovery process was modeled using a linear formulation due to the unavailability of information from past earthquakes. SR for the selected bridge classes was calculated in terms of the seismic intensities to be applied for decision-making procedures during pre- and postearthquake assessments. [ABSTRACT FROM AUTHOR]

The present design guidelines for rigid-faced (RF) geosynthetic reinforced soil (GRS) walls recommend a minimum toe embedment depth as a geometric requirement. The toe condition effect is ignored in these designs. Development of tools for serviceability design and refinement of present design methods require a complete understanding of the toe condition's role. Finite element analysis of RF-GRS walls is carried out in this study for different toe conditions, such as fixed, rotating and frictional toe, representing different construction methods. The analysis of fixed toe conditions shows 3–5 times lesser deformations and 10–20 times lesser loads in bottom reinforcements compared to other toe conditions. Reduced reinforcement stiffness at the bottom of the wall for a fixed toe condition has a negligible effect on deformations. The fascia experiences high bending moments at the bottom of the wall with fixed toe conditions. Frictional toe condition mobilizes both sliding and rotation modes of wall deformations. It also shows toe force increasing by 5–20% for embedment depth increase by 6 times. The results for rotating toe with restrained sliding show higher top displacements than other toe conditions. The use of stiffer reinforcements at the wall top reduces such rotations. Possible design concepts to impart toe fixity in the field are also discussed. [ABSTRACT FROM AUTHOR]

Soil-structure interaction (SSI) is the relationship between soil response affecting structure movement and vice versa. SSI has long been thought to benefit a structure's seismic response. It is proposed that neglecting SSI in design results in conservative results. Various design standards either permit a decrease in the total seismic coefficient because of SSI or suggest that it be disregarded entirely to simplify the complexity of analyses. However, findings from prior seismic disasters, such as the 1989 Loma Prieta and the 1995 Kobe Earthquakes, reveal that SSI can be detrimental in some situations, especially in pile-supported structures. Although it is necessary in certain modeling cases to consider soil-pile-structure interaction (SPSI), there is a lack of knowledge detailing which approach to utilize for an SPSI problem and which approach does or does not include the effects that provide simplification or complexity in modeling. In this paper, modeling issues on SPSI are investigated in general, considering different approaches presented in the literature. It is predicted that the findings of this paper will provide invaluable knowledge for researchers in the geotechnical and structural engineering fields. [ABSTRACT FROM AUTHOR]

Based on the hysteretic tests of steel-reinforced reactive powder concrete (RPC) columns and reinforced RPC columns, the finite element numerical models of these two kinds of RPC columns were established by OpenSees (2016). The feasibility of the model was verified by comparing the results of tests and simulation. On this basis, the nonlinear analysis of seismic performance of cross-shaped-steel-reinforced RPC columns was carried out. The influences of different factors such as longitudinal reinforcement ratio, steel sectional resistance moment, RPC grade, steel strength and section form of shape steel on the hysteretic performance were investigated. Finally, the hysteretic model of cross-shaped-steel-reinforced RPC columns was established. The results showed that, compared with H-shaped-steel-reinforced RPC columns, the peak bearing capacity of cross-shaped-steel-reinforced RPC columns was increased by 21.2%, but the displacement ductility was obviously reduced. With the increase of slenderness ratio, the lateral stiffness and horizontal bearing capacity of cross-shaped steel RPC columns decreased rapidly. In addition, the peak load was improved with the increase of RPC strength, steel sectional resistance moment and longitudinal reinforcement ratio. The hysteretic model was consistent with the simulation results, which can effectively predict the hysteretic characteristics of cross-shaped-steel-reinforced RPC columns. The research results can provide a theoretical basis for the engineering design and application of cross-shaped-steel-reinforced RPC columns. [ABSTRACT FROM AUTHOR]

Segmental tunnel is widely adopted in the urban transportation system, thereby its seismic resilience is a cornerstone for resilient cities. The segmental tunnel is an assembly of reinforced concrete segments, bolts, gaskets, gaps, etc., and exhibits highly nonlinear behavior when subjected to external loadings. Yet, in practice, its seismic response is generally estimated via a holistic modeling approach where the segmental tunnel is represented by a homogeneous beam or shell element with equivalent stiffness. Here, a multi-contact joint-based model is developed for a segmental tunnel, incorporating the nonlinearities embedded in the assembly with acceptable computational costs. The reinforced concrete segment is represented as the displacement-based fiber beam element, whereas the complex interaction among the configurations of the joint, i.e. bolt, gasket, and contacting concrete, is modeled via the zero-length section element. The proposed model's accuracy is validated via a series of experimental data under three loading scenarios. A sensitivity analysis demonstrates that the mechanical response of segmental tunnels highly relies on the assembly configurations. The proposed model is implemented to investigate the seismic response of a typical segmental tunnel under various ground motions, demonstrating its applicability in seismic safety assessments, particularly in capturing the nonlinear response of segmental tunnels under high-intensity earthquakes. [ABSTRACT FROM AUTHOR]

This paper provides new and useful insights into the performance and efficiency of geotechnical seismic isolation (GSI) systems with gravel-rubber mixtures containing 10%, 25% and 40% volumetric rubber content (VRC). Finite element numerical models were developed in OpenSees and subjected to sinusoidal ground motions with varying input base acceleration and frequency. The best seismic performance was attained for VRC = 40% at a frequency of 8 Hz. Using a newly developed GSI efficiency index, the energy dissipation efficiency of VRC = 40% was found to vary between good to excellent, while that of VRC = 10% and 25% is poor. [ABSTRACT FROM AUTHOR]

Six hybrid steel and PVA fiber cementitious composite (S&PFCC)‐encased concrete‐filled steel tube (CFST) columns were designed and fabricated, and the effects of axial compression ratio, core concrete strength grade and steel tube thickness on the seismic performance of composite columns were studied. The test results show that the increase of core concrete strength can obviously improve the bearing capacity and energy dissipation capacity of composite column and can restrain the strain growth rate of steel tube after yielding. Low axial compression ratio and thicker steel tube thickness can improve the overall seismic performance of composite columns. Three calculation methods are modified, and the modified An method can predict the lateral bearing capacity of composite column well. Finally, based on the OpenSees finite element software, the seismic performance of the CFST column wrapped in S&PFCC is simulated to verify the test, and the numerical study shows that the seismic performance of the composite column can be optimized by increasing the steel fiber content, while PVA fiber has a weak effect in the elastic stage, and can effectively improve the ductility of the composite column in the plastic stage. [ABSTRACT FROM AUTHOR]

In recent decades, research on renewable energy has been boosted by the emerging awareness of energy security and climate change and their consequences, such as the global cost of adapting to the climate impacts. Both onshore and offshore wind turbine farms have been considered as one of the main alternatives to fossil fuels. Their development currently involves seismic-prone areas, such as the Californian coastline and East Asia, where the risk of soil liquefaction is significant. Onshore wind turbines (OWTs) typically are founded on shallow rafts. Their operation can be affected strongly by the simultaneous presence of intense earthquakes and wind thrust, which may cause remarkable permanent tilting and loss of serviceability. In these conditions, accurate evaluation of the seismic performance of these structures requires the development of well-validated numerical tools capable of capturing the cyclic soil behavior and the build-up and contextual dissipation of seismic-induced pore-water pressures. In this paper, a numerical model developed in OpenSees, calibrated against the results of dynamic centrifuge tests, was used to evaluate the influence of some ground motion intensity Measures of the seismic behavior of OWTs included the amplitude, frequency content, strong-motion duration, and Arias intensity (energy content) of the earthquake, together with the effect of a coseismal wind thrust, which is not well explored in the literature. The seismic performance of an OWT was assessed in terms of peak and permanent settlement and tilting, the latter of which was compared with the threshold of 0.5° typically adopted in practice. [ABSTRACT FROM AUTHOR]

Empirical studies have demonstrated a significant interaction between non-linear flexural and shear responses in reinforced concrete shear walls. This paper investigates the implications of shear-flexural interaction (SFI) on the seismic performance of high-rise reinforced concrete dual frame-wall systems. Structures with three different heights (20, 25 and 30 stories) are analyzed. Comparative structural analyses are conducted using two modeling approaches for shear walls: one incorporating SFI and the other neglecting it. A set of ground motion records from the Federal Emergency Management Agency (FEMA) P695 is utilized to perform incremental dynamic analysis, facilitating a detailed evaluation of structural behavior under seismic loading. Collapse risk assessment encompasses seismic hazard analysis and the determination of collapse fragility. Furthermore, the collapse performance is appraised following the FEMA P695 methodology. The results underscore the substantial impact of SFI on both seismic performance and collapse risk in high-rise reinforced concrete structures. Specifically, integrating SFI into shear wall modeling results in elevated collapse risk and diminished ACMR. This underscores the pivotal role of SFI in shaping structural resilience. [ABSTRACT FROM AUTHOR]

OpenSees, a framework for nonlinear structural analysis, has significantly advanced seismic research and practice. The introduction of OpenSeesPy in 2018, which integrated Python as an interpreter alongside TCL, greatly enhanced the framework's utility by leveraging Python's robust data management tools. However, the legacy practice of exporting results for external processing, inherited from the TCL era, remains a challenge. This paper addresses this need with opseestools, a Python library designed to streamline OpenSeesPy workflows. It provides tools for model setup, analysis, and results post-processing, seamlessly integrating with popular scientific libraries like Pandas, Numpy, and joblib. As an open-source project on PyPI, opseestools is backed by a GitHub repository featuring practical examples, making it easily accessible for the community.

Based on experimental data of composite beam-reinforced concrete column frames, a corresponding finite element (FE) numerical model was established using the OpenSees. By comparing experimental and simulation results, the feasibility of this model was verified. Furthermore, an in-depth nonlinear analysis of the seismic performance of the composite beam-reinforced concrete column frames was conducted. This analysis focused on the effects of various factors such as reinforcement ratio of slabs and columns, the section modulus of steel, axial compression ratio, concrete strength, and steel strength on the load-displacement of the such frames. Ultimately, based on the test and simulation results, a new load-displacement hysteretic model for composite beam-reinforced concrete column frames was derived, and its calculation results were compared with those from the test and simulation. The comparison indicated that the derived formula is in good agreement with the experimental data, demonstrating its applicability in structural calculation and analysis.

Conducting a structural fire analysis for automated steel parking structures present a complex challenge due to the vulnerability of steel structures to high-temperature exposure, the unpredictability of fire source locations, and the enhanced thermal loading due to high concentration of vehicles in a compact area. This study conducted a performance-based assessment (PBA) of a fully automated multi-storey steel parking structure under various fire scenarios. The assessment employed Fire Dynamic Simulator (FDS) to simulate the fire behavior in different scenarios and record the temperature developments within the structure. OpenSees was utilized to perform the subsequent thermo-mechanical analysis and obtain the fire responses of the parking structure. The fire analyses demonstrated that the ignition location and ventilation conditions within the structure considerably affects fire propagation and structural responses. Fire cases initiated on the first floor led to a slightly higher drift ratio than those initiated on the 9th floor. The PBA based on strain and drift ratio led to different results. Cases 1, 2, 4, and 6 maintained life safety based on drift ratios, and strain results indicated a collapse prevention level. For centrally located fire cases, the drift ratios were at collapse prevention level while based on strain values, the elements already exceeded the collapse prevention limit. Under all fire cases, the ultimate performance level of the structure has exceeded the collapse prevention level. The findings highlight the necessity of employing fire safety measures in multi-storey parking structures and enhancing their fire resilience.

Earthquake-induced soil liquefaction can cause soil settlement around piles, resulting in drag load and pile settlement after shaking stops. Estimating the axial load distribution and pile settlement is important for designing and evaluating the performance of axially loaded piles in liquefiable soils. Commonly used neutral plane solution methods model the liquefiable layer as an equivalent consolidating clay layer without considering the sequencing and pattern of excess pore pressure dissipation and soil settlement. Moreover, changes in the pile shaft and the tip resistance due to excess pore pressures are ignored. A TzQzLiq numerical model was developed using the existing TzLiq material and the new QzLiq material for modeling liquefaction-induced downdrag on piles. The model accounts for the change in the pile's shaft and tip capacity as free-field excess pore pressures develop or dissipate in soil. The developed numerical model was validated against data from a series of large centrifuge model tests, and the procedure for obtaining the necessary information and data from those is described. Additionally, a sensitivity study on TzLiq and QzLiq material properties was performed to study their effect on the developed drag load and pile settlement. Analysis results show that the proposed numerical model can reasonably predict the time histories of axial load distribution and settlement of axially loaded piles in liquefiable soils both during and postshaking.

Liquefaction‐induced lateral spread is a kind of ground deformation caused by soil liquefaction, which is a danger to houses, roads and other infrastructures. In order to systematically investigate the influence law of different parameters on lateral displacement, this paper establishes a numerical model of the seismic responses of gently sloping grounds through the open‐source finite element software OpenSees and carries out a large number of calculations considering various working conditions. Based on the calculation results, eXtreme Gradient Boosting (XGBoost) and random forest (RF) regression are used to build the proxy models for lateral spread displacement prediction. The finite element model was verified by using the multiple VELACS No. 2 centrifuge experiments. Finally, the model was interpreted using SHapley Additive exPlanation (SHAP) method. The results of the model training showed that both models were able to achieve a good fit to the numerical calculation results, with the RF model having a smaller prediction error for the centrifuge experiments. The model interpretation results showed that the modified cumulative absolute velocity (CAV5) was the most important input variable in the model, and the importance of ground slope (S), relative density (Dr) and thickness of liquefiable soil layer (HL) was relatively high. In addition, the influence of each parameter on the lateral displacement is consistent with the actual situation, reflecting the rationality of the model prediction process. In addition, the results showed that there is a threshold for the modified cumulative absolute velocity (CAV5) and Arias intensity (Ia) that leads to a significant increase in lateral displacement. The thresholds of CAV5 and Ia are 1.3 g s and 1.0 m/s, respectively. These thresholds are in good agreement with the thresholds for triggering the overall initial liquefaction of the soil layer determined by related studies, which provides a reference for the evaluation of liquefaction‐induced lateral displacement. [ABSTRACT FROM AUTHOR]

The findings of numerous analytical/computational studies, tests, and in-situ observations have highlighted the importance of the deck-abutment-backfill interaction on the seismic response of bridges. These findings have allowed various researchers to develop models for the nonlinear behaviour of the abutment-backfill system. Such models have been extensively used in research, and the simpler among them have been adopted by modern seismic codes and guidelines and have also been incorporated in programs for the nonlinear analysis of structures. Although large-scale tests have captured the behaviour of the abutment-backfill system subsequent to the attainment of peak strength, this critical phase of the response has neither been studied to a sufficient extent from the analysis point of view, nor included in the constitutive models of available nonlinear analysis programs. The softening region of the response of the backfill has been addressed using a number of hardening/softening plasticity models that are rarely used in practical analysis wherein simpler models (like Winkler springs) are typically preferred. Capturing the post-peak range of the abutment-backfill response is very significant in seismic fragility analysis of bridges for the definition of limit states close to failure. In the above context, the main aim of the work presented herein is to introduce a new model capturing this range of the backfill response; it is an extended version of the 'Hyperbolic Gap' 'material' in OpenSees, named 'Hyperbolic Gap Softening' material, which allows the user to define a set of parameters that describe the softening branch of the backbone curve of an abutment-backfill system. In addition to tests of the new model using a simple structural configuration, results of response history analyses of a case-study bridge with different abutment-backfill properties are also reported, with a view to verifying the applicability of the proposed model and assessing the importance of capturing the post-peak abutment-backfill behaviour on the assessment of the seismic response of a bridge. [ABSTRACT FROM AUTHOR]

Kathmandu, located in a high seismic zone, predominantly features irregular structures among its building stock. These structures are particularly susceptible to severe damage during seismic events, primarily due to torsional effects. Traditional seismic designs rely particularly on fixed-base conditions that underestimate forces and displacement primarily on soft soil conditions leading to irrational design practices. This study aims to quantify the seismic performance of buildings on various base conditions through fully nonlinear Soil-structure Interaction (SSI). The soil nonlinear behaviour was modelled using the Pressure-Independ-Multi-Yield (PIMY) material with an octahedral shear stress-strain backbone curve. Three distinct soil types were considered, and structures with irregular plan configurations were modelled using finite elements in both Opensees and STKO platforms. Structural performance was analyzed through nonlinear dynamic analysis, and outputs were evaluated based on seismic parameters. Comparing nonlinear SSI with linear SSI and fixed-base conditions revealed a significant increase in structural response, expressed in terms of displacement, drift ratio, and base shear. The magnitude of diaphragm rotation was found to be influenced by a combination of building torsional irregularity and SSI effects. It is suggested that the conventional practice of using the torsional irregularity ratio as a measure of torsional irregularity be revised and enhanced to better account for these influences. It has been quantified that torsional irregularity has a relatively lesser impact on displacements, drifts, and base shear compared to SSI. In all cases, fixed-base conditions consistently exhibited the minimum response. The study explored that linear SSI and fixed-base conditions tend to underestimate structural responses, while nonlinear SSI coupled with dynamic analysis provides a more accurate representation of realistic structural behaviour for seismic design particularly in soft soil cases.

It is widely acknowledged that the effects of soil-structure interaction (SSI) can have substantial implications during periods of intense seismic activity; therefore, accurate quantification of these effects is of paramount importance in the design of earthquake-resistant structures. The analysis of SSI is typically conducted using either direct or substructure methods. Both of these approaches involve the use of numerical models with truncated or reduced-order computational domains. To ensure effective truncation, it is crucial to employ boundary representations that are capable of perfectly absorbing outgoing waves and allowing for the consistent application of input motions. At present, such capabilities are not widely available to researchers and practicing engineers. In order to address this issue, this study implemented the Domain Reduction Method (DRM) and Perfectly Matched Discrete Layers (PMDLs) in OpenSees. The accuracy and stability of these implementations were verified through the use of vertical and inclined incident SV waves in a two-dimensional problem. In terms of computational efficiency, PMDLs require a shorter analysis time (e.g., with PMDLs, the analysis concluded in 35 min as compared to 250 min with extended domain method) and less computational power (one processor for PMDLs against 20 processors for the extended domain method) thus offering a balance between accuracy and efficiency. Furthermore, illustrative examples of the aforementioned implemented features are presented, namely the response analysis of single-cell and double-cell tunnels exposed to plane waves inclined at an angle.

Following recent earthquakes, precast buildings exhibited a strong seismic vulnerability related to the presence of closure external panels. The aim of this work is to simulate the seismic response of existing single-storey precast buildings in the case of explicit modelling of external panels. The considered case studies are precast buildings representative of the Italian building stock in the 1970s and 1990s, characterised by two different cladding systems, namely, masonry infills and reinforced concrete precast panels, respectively. The explicit modelling of infills and panels, typically introduced solely as participating masses, provided insights into their actual contribution on the global structural behavior. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive probabilistic framework is proposed and adopted to perform seismic reliability and risk analysis of existing link slab (LS) bridges, representing a widely diffused structural typology within the infrastructural networks of many countries worldwide. Unlike classic risk analysis methods, innovative fragility functions are used in this work to retrieve more specific and detailed information on the possible failure modes, without limiting the analysis to the global failure conditions but also considering several intermediate damage scenarios (including one or more damage mechanisms), and providing insights on the numerosity of elements involved within a given damage scenario. Reliability analyses are performed on a set of LS bridges with different geometries (total lengths and pier heights) designed according to the Italian codes enforced in the 1970s. Accurate numerical models are developed in OpenSees and Multiple-Stripe nonlinear time–history analyses are carried out to build proper demand models, from which fragility functions are determined according to two limit states: damage onset and near-collapse. Mean annual rates of exceeding are thus estimated through the convolution between the hazard and the fragility. The results shed light on the main failure mechanisms characterizing this bridge typology, highlighting how different levels of risk (hence safety margins) can be associated with failure scenarios that differ in terms of elements/mechanisms involved and damage extension. Such a higher level of detail in the risk analysis may be useful to better quantify post-earthquake consequences (e.g., costs and losses) and define more tailored retrofit interventions. A comparison of the reliability levels associated with bridges of the same class with different geometries is finally presented. [ABSTRACT FROM AUTHOR]

This paper presents application of ASCE/SEI 41–17 nonlinear seismic analysis and evaluation procedures to the 10-story reinforced concrete building tested on the E-Defense shake table in December 2015. Primary lateral load resisting system of the building was reinforced concrete frame in the longitudinal direction and RC wall in the transverse direction. Analytical models were developed in OpenSees with nonlinear wall, beam, and column elements, as well as with linear elastic and two types of nonlinear beam-column joint elements: (1) modeling parameters that follow ASCE/SEI 41–17 recommendations, and (2) modeling parameters derived using data from relevant experimental results. Computed responses for the analytical models of the building and predicted damage are compared with measured responses and observed damage for strong motion records from 50 and 100% Kobe earthquake excitations. Results comparisons indicate that the ASCE/SEI 41–17 nonlinear dynamic evaluation procedures are overall able to reasonably identify the general damage extent and distribution for both frame and wall directions. Analysis results further suggest that the beam-column joint modeling parameters in ASCE/SEI 41–17 for nonlinear dynamic procedures likely overestimate the rate of strength loss with increasing deformation demands revealing a potential need for review and update of the joint shear strength and nonlinear modeling parameters and acceptance criteria. [ABSTRACT FROM AUTHOR]

Floor diaphragms are structural elements mainly responsible for transmitting lateral loads to the adjoining vertical members of the Seismic-Force-Resisting System (SFRS). Under significant seismic events, the actual in-plane stiffness of floor diaphragms affects patterns of load distribution in-between horizontal and vertical elements and, as such, contributes to the local nonlinear response and the global dynamic behavior. However, in SFRS with mass timber and hybrid timber-based floor diaphragms, neither design provisions nor procedures exist to account for its in-plane flexibility. To highlight the influence of the actual in-plane stiffness of diaphragms on a timber-steel hybrid building system, this paper analyzes its dynamic response via nonlinear dynamic analysis. The OpenSees framework is adopted to develop three finite-element building models that feature diaphragms with (i) rigid behavior, (ii) actual members and connections diaphragm subassembly behavior, including panel-to-panel slab connections, or (iii) neglecting the contribution of the slab connections, respectively. The SFRS of the building entails a Special Concentrically Braced Frame whose nonlinear behaviors are explicitly simulated, including global buckling, tensile yielding, and post-buckling behaviors. The collapse fragility analysis reveals that the conditional probability of exceeding all three considered limit states given any level of ground motion intensity for the SFRS equipped with the CLT-steel floor diaphragm is close to that of the SFRS with rigid diaphragm behavior. Removal of CLT panel-to-panel connections attracts disproportionate and excessive lateral deformation demands towards the unbraced frames due to the increased in-plane diaphragm flexibility. [ABSTRACT FROM AUTHOR]

Based on the hysteretic tests of steel-reinforced reactive powder concrete (RPC) columns and reinforced RPC columns, the finite element numerical models of these two kinds of RPC columns were established by OpenSees (2016). The feasibility of the model was verified by comparing the results of tests and simulation. On this basis, the nonlinear analysis of seismic performance of cross-shaped-steel-reinforced RPC columns was carried out. The influences of different factors such as longitudinal reinforcement ratio, steel sectional resistance moment, RPC grade, steel strength and section form of shape steel on the hysteretic performance were investigated. Finally, the hysteretic model of cross-shaped-steel-reinforced RPC columns was established. The results showed that, compared with H-shaped-steel-reinforced RPC columns, the peak bearing capacity of cross-shaped-steel-reinforced RPC columns was increased by 21.2%, but the displacement ductility was obviously reduced. With the increase of slenderness ratio, the lateral stiffness and horizontal bearing capacity of cross-shaped steel RPC columns decreased rapidly. In addition, the peak load was improved with the increase of RPC strength, steel sectional resistance moment and longitudinal reinforcement ratio. The hysteretic model was consistent with the simulation results, which can effectively predict the hysteretic characteristics of cross-shaped-steel-reinforced RPC columns. The research results can provide a theoretical basis for the engineering design and application of cross-shaped-steel-reinforced RPC columns.