Seismic Performance Evaluation Research Articles

Seismic performance evaluation of self-centering balloon-framed CLT building

Balloon-framed cross-laminated timber (CLT) construction has a number of advantages when compared to platform-type construction; however, many international standards only include provisions for the latter as there is little research reported on the seismic performance of the former. In this paper, a seismic fragility assessment of a 4-storey balloon-framed CLT building in Vancouver, Canada, is presented. This structure is the first in North America that adopts a self-centering friction-based technology for the hold-downs (HDs). The seismic performance of the building was assessed by performing incremental dynamic analysis (IDA) on a three-dimensional finite element model using Cascadia Subduction Zone ground motions, and compared to a second building model with conventional dowel-type HDs. The analyses at the design intensity level showed that the self-centering building had an average maximum inter-story drift ratio of 0.67%, well below the 2.5% drift limit specified in the National Building Code of Canada. Based on the IDA and taking into account uncertainties, the building had a collapse margin ratio of 2.96 and a 5.2% probability of collapse at the design level. Compared to the conventional HDs, the friction-based HDs did not improve the building’s collapse capacity, but reduced the building drift by more than 20% at lower damage states, demonstrating the effectiveness of designing balloon-framed CLT structures with a resilient self-centering HDs in high seismic zones.

ASCE/SEI 7‐compliant site‐specific evaluation of the seismic demand posed to reinforced concrete buildings with real and simulated ground motions

AbstractState‐of‐the‐art seismic design and assessment methodologies rely on the utilization of ground‐motion records scaled to site‐specific risk‐targeted spectra to perform nonlinear time‐history analyses and estimate mean structural demands. Motivated by the discrepancies in structural response estimates resulting from different selection and scaling methods, this study assesses the implications of utilizing site‐specific simulated ground motions from 3‐D physics‐based wave‐propagation models as opposed to historical records from worldwide catalogs in ASCE/SEI7‐compliant procedures for seismic performance evaluations. A suite of validated realizations of an M7 Hayward Fault earthquake in the San Francisco Bay Area and two modern reinforced concrete moment‐resisting frame buildings are utilized as a case study. The 2014 USGS earthquake hazard and probability maps are employed for the hazard calculations, and the PEER NGA‐West2 database is used for the selection of the real ground motions. The building models are coupled with the simulated and real ground motions to perform a total of 30,552 nonlinear time‐history analyses. Structural demands obtained from real and simulated motions are examined and compared at the regional‐scale in terms of peak interstory drift ratio median and dispersion, and localization along the building height. The correlations between observed structural responses and ground‐motion features are discussed to potentially inform current code‐compliant methodologies for ground‐motion selection. Results show that utilizing site‐specific simulated ground motions that incorporate path, fault geometry, and site‐condition effects as opposed to historical ground‐motion records may lead to differences in the structural demands above 50%. Such differences are highly spatially variable throughout the region and difficult to predict.

Analisis Kinerja Seismik Gedung dengan Pushover Analysis (Studi Kasus: Gedung Perkantoran Tiga Tingkat yang Runtuh Akibat Gempa Palu 2018)

Indonesia is an earthquake-prone country. The 2018 earthquake in Palu, Sulawesi, caused significant damage or collapse of the buildings. This research is aimed to evaluate the seismic performance of a three-story office building at Tadulako University and to evaluate what caused the collapse of the building. Evaluation of seismic performance was conducted using the default plastic hinge in SAP2000. The analysis results showed that the plastic hinge occurred first at the end of the beam, followed by the plastic hinge at the end of the column. The performance point from the intersection of the capacity curve and capacity spectrum based on ATC-40 indicated that the performance level of the building was damage control, which means that the building can resist seismic force and has a low risk of human death. These results did not represent the post-earthquake condition in which the building collapsed due to failure of the beam-column joint because the shear reinforcement was not installed in the beam-column joints. Further studies are necessary in order to develop an analysis model, including the failure model of the beam-column joint.

Real-time hybrid simulation for seismic control performance evaluation of an active inerter damper system

Active structural control has been recognized as an intelligent method to mitigate seismic vibrations of structures by generating superior supplemental damping in structural engineering studies. Recently, active inerter damper (AID) that consists of an inerter and an actuation system has been evolved from active mass damper. AID has advantages of small volume and light weight because of the mechanical properties of inerter that amplify the inertial force by numerous times the mass of the inerter; therefore, installation of an AID system becomes simple in real engineering applications. However, it is difficult to validate seismic control performance of a multi-story specimen with an AID system in structural laboratories limited by capacity of testing facilities. In this study, real-time hybrid simulation (RTHS), which combines experimental testing with numerical simulation is applied to evaluate the control performance of the AID system. A 10-story shear building is numerically simulated as a benchmark building controlled by the AID, which is physically driven in the structural laboratory. A modal linear-quadratic regulator (LQR) with optimized weighting matrices is designed for generating the desired control force for the AID. Meanwhile, a surrogate model of the modal LQR is trained and implemented for comparison purpose. In addition, two force tracking controllers are implemented to reproduce the desired control force through the AID. Furthermore, three approaches for acquiring the achieved force of AID are proposed and employed to feedback the control force to the numerical model for completing the RTHS loop. Finally, mitigation of seismic response is compared and discussed methodically based on the RTHS results. This study suggests the most appropriate RTHS technique for evaluating the control performance of buildings with the AID system.

Convolutional neural network-based seismic fragility analysis of subway station structure considering spatial variation of site shear-wave velocity

Prior research demonstrated that the uncertainty of soil parameter can significantly impact the seismic response analysis and seismic performance evaluation of underground structures. To this end, the seismic response of a three-story, three-span subway station embedded in a typical layered engineering site was investigated in this study and the uncertainty of soil parameters was explicitly considered using the shear-wave velocity interlayer correlation model. In addition, an incremental dynamic analysis considering the uncertainty of the shear-wave velocity was performed using the one-dimensional convolutional neural network (1D-CNN) model as a surrogate model for the traditional finite element method. The results indicate that the uncertainty of soil shear-wave velocity increases the average PGA values for minor, moderate, and severe failures with a probability of exceeding 50% by about 10%, and increases the logarithmic standard deviation by about 40%. When considering the uncertainty of shear-wave velocity, the discreteness of the fragility curve will increase. Moreover, the rightward shift of the fragility curve midpoint leads to a comparatively more safety seismic performance evaluation of the structure under significant seismic input.

Seismic performance evaluation of steel circular hollow section bridge piers with corroded ends

Seismic performance evaluation of steel circular hollow section bridge piers with corroded ends

Evaluation of a nonlinear TMD seismic performance for multi-degree of freedom structures

Evaluation of a nonlinear TMD seismic performance for multi-degree of freedom structures

Seismic performance and replaceability evaluation of multi-section energy-consuming beams

Seismic performance and replaceability evaluation of multi-section energy-consuming beams

Hybrid Simulation for Evaluation of Seismic Performance of Highway Bridge with Pier Retrofitted Using Fe-SMA Strips

The present research investigates the use of Fe-based shape memory alloy (SMA) strips for seismic retrofitting of rehabilitated RC bridge pier models. Four severely damaged bridge pier models were first rehabilitated by RC jacketing to retrieve at least their lost strength. Three configurations of Fe-SMA strips namely hoop (H), end-anchored (EA), and a combination of previous two approaches (EAH) were adopted. Prestrained Fe-SMA hoops, placed in the plastic hinge region of the bridge pier model, aims at utilizing the recovery stress developed upon thermal activation for application of active confinement pressure on the test specimen. The EA Fe-SMA strips utilize precompression developed in the concrete in the plastic hinge region of the test specimen. The EAH reinforcement scheme was studied for both precompression and active confinement. To compare the seismic performance of the various Fe-SMA retrofitted test specimens with respect to the control specimen, hybrid simulation (pseudodynamic) of an existing highway bridge located in Tripura, India was carried out with the scaled bridge pier test models as experimental elements. Earthquake excitations of different intensity levels were applied in a sequential manner to analyze the behavior of the structure over a damage spectrum ranging from minor cracking to major damage. To determine the ultimate capacity of the test specimens, cyclic tests were carried out after completion of a hybrid simulation. Bridge pier specimens with Fe-SMA in the form of EA reinforcement exhibited enhanced load-carrying capacity but marginal improvement in ultimate displacement while Fe-SMA hoops improved the ultimate displacement of the test specimen with marginal improvement in the peak lateral load. A combination of EA and hoop Fe-SMA reinforcement was found to be more efficient in improving all the seismic performance parameters such as lesser damage and higher load-carrying capacity, stiffness, and energy-dissipation capacity.

Seismic Performance Evaluation of Friction Damper and Yielding Metallic Damper in Steel Frame

In recent decades, various control systems have been studied to reduce the vibrations of structures under dynamic forces. Generally, types of structural control systems are classified into energy dissipation systems and seismic isolation systems. Examples of energy dissipation systems include metallic yielding dampers, friction dampers, viscoelastic dampers, viscous dampers, tunable mass dampers, and tunable liquid dampers. This article investigates the seismic performance of friction dampers and metallic yielding dampers in steel frames, as well as the performance of a two-story steel frame strengthened with metallic yielding dampers and combined with friction dampers. For this purpose, five two-story steel frames with eight-story divergent braces were examined: a frame without a damper, a two-story frame with metallic yielding dampers, a two-story frame with friction dampers, a two-story frame with the first floor having friction dampers and the second floor having metallic yielding dampers, and a two-story frame with the first floor having metallic yielding dampers and the second floor having friction dampers. The results show that the use of dampers increases the energy dissipation of the structure and reduces the maximum displacements induced in the structure as well as the base shear. The effect of metallic yielding dampers on reducing the base shear is greater than that of friction dampers, while the effect of friction dampers on increasing energy dissipation and reducing displacements induced in the structure is greater compared to metallic yielding dampers

Seismic Performance Evaluation of Wharf Based on ASCE 61-14

The adequacy of the structural performance of a wharf in withstanding seismic loads is of paramount importance. Therefore, this research aims to conduct an accurate pushover analysis on the adequacy of a wharf located in North Sulawesi, Indonesia. The study provides a comprehensive overview of the seismic performance of the wharf by examining displacement and strain parameters of its plastic hinge components under various loading conditions. To simulate accidental torsion, the wharf structure was analyzed by introducing variations in the eccentricity offset of the lateral pushover load of -5%, 0%, and 5% from the center of mass. The analysis of the torsion behavior involved a comprehensive examination of four control points located at each corner of the wharf plan. Additionally, the investigation took into account, the crucial aspect of soil-structure interaction by considering the equivalent fixity depth of the pile, which was used to evaluate the fixity length of the structure. In order to determine the target displacement of the wharf, analysis was performed in accordance with the established methodologies outlined in FEMA 356. It is also important to note that the seismic performance of the wharf was evaluated based on acceptance criteria in the form of strain limits imposed on various components, including concrete elements, reinforcing steel, and steel pipes, as prescribed by ASCE 61-14. In this study, a total of 30 models were examined, and the obtained results showed that the structure exhibited controlled and repairable damage even when subjected to a 475-year earthquake return period (CLE: Contingency Level Earthquake). Following this, the analysis of variations in displacement control point served to determine the inherent torsion exhibited by the structure, and the introduction of different lateral load eccentricity offsets and variations in pushover loading direction were found to contribute to the increased displacement and strain in the plastic hinge components.

Probabilistic Evaluation of Seismic Performance of Steel Buildings with Torsional Irregularities in Plan and Soft Story under Mainshock-Aftershock Sequence

Due to the tectonic plate movement, numerous aftershocks may occur following an earthquake. There are several real mainshock-aftershock ground motion records in which the peak ground acceleration of aftershock is greater than that of the mainshock. Furthermore, irregularities such as soft story and torsional irregularity may change the structural behavior under the influence of earthquakes. This study investigates the fragility curves associated with the three-, five-, and eight-story models with steel moment-resisting frames under the main earthquake and mainshock-aftershock sequence to probabilistically evaluate the aftershock impacts on the steel structures with irregularities in the plan and height. The seismic fragility curves were calculated for four damage levels by selecting the relative displacement capacity at seismic performance levels of slight, moderate, extensive, and complete damage from the US HAZUS code. The analysis was done using structural reliability relationships and incremental dynamic analysis with the OpenSees software platform. The analytical results showed that the structures with soft-story and torsional irregularity were more vulnerable with an increasing number of stories. Also, aftershocks were found to have a more destructive effect on low-rise models. The probability of structural collapse in a given peak ground acceleration for a damaged state due to the mainshock-aftershock sequence is higher than that of the mainshock sequence.

Seismic performance of bidirectional bolted drilled cut RBS-CFT connections under cyclic loads

Welded connections were widely used in different regions of the world for ease of fabrication and good performance under gravity load. However, Northridge (1994) and Kobe (1995) earthquakes demonstrated that seismic performance of welded connections has been inferior as compared to that of bolted connections. Reduced beam section (RBS) has been one of the effective methods to enhance seismic performance in terms of energy dissipation capacity and ductility. Drilled-cut RBS-CFT connections have been gaining acceptance for enhancing overall seismic performance of steel moment resisting frames. However, no comparative study has been reported in the literature on RBS-CFT connection with bidirectional bolts for evaluation of their seismic performance. In view of the above, experimental study has been carried out for evaluation of seismic performance of two variants of RBS-CFT connections with constant drilled cut (CD-cut) and varied drilled cut (VD-cut) RBS. Both the drilled cut RBS-CFT connections are found to be semi-rigid in nature and exhibited stable hysteretic behavior. Test results showed that the cumulative energy dissipation capacity in the VD-cut connections is marginally higher than CD-cut connection. VD-cut RBS-CFT connections effectively reduced the lateral-torsional deformation. The load-carrying capacity and stiffness degradation ratio of VD-cut RBS-CFT connection is higher than CD-cut RBS-CFT connection. Damping of the both connections are nearly of similar order. Recorded strain data of both connections showed that plastic hinge confined only on drilled zone of the beam. Further, a detailed numerical simulation of force-deformation envelope curve of RBS-CFT connections was carried out using ABAQUS software. Simulated force-deformation envelope curves are found to be in close agreement with those obtained from experimental investigation. Both connections meet the seismic requirements of the AISC specified for composite special moment-resisting frames (SMRFs) by achieving rotational capacity of 0.04 radians without any damage in the joint panel region.

Development of a pseudostatic method for seismic performance evaluation of rocking bridge foundations

AbstractPseudostatic analysis can be an efficient approach to evaluating the dynamic response of structures for a preliminary design. In this paper, we present a pseudostatic method based on a pushover analysis to assess the seismic performance of bridge piers supported by rocking‐governed shallow foundations. The method has two stages. In the first stage, the capacity spectrum method (CSM) is applied to evaluate the maximum acceleration and displacement response of the bridge system. To have an appropriate system damping ratio in the CSM, we propose a method to consider various earthquake energy dissipation mechanisms for the pier and foundation. In the second stage, the footing settlement is evaluated based on the maximum footing rotation; an incrementally cyclic pushover analysis with a fixed footing rotation increment is performed to estimate the footing settlement. Examples are presented to demonstrate the applicability of the proposed method and the results of the proposed method are compared with the dynamic analysis results. Compared with the conventional CSM, the proposed method improves the estimation of system damping and can estimate the settlement after earthquakes.

Seismic performance evaluation of plastered cellular lightweight concrete (CLC) block masonry walls

The current research presents a novel and sustainable load-bearing system utilizing cellular lightweight concrete block masonry walls. These blocks, known for their eco-friendly properties and increasing popularity in the construction industry, have been studied extensively for their physical and mechanical characteristics. However, this study aims to expand upon previous research by examining the seismic performance of these walls in a seismically active region, where cellular lightweight concrete block usage is emerging. The study includes the construction and testing of multiple masonry prisms, wallets, and full-scale walls using a quasi-static reverse cyclic loading protocol. The behavior of the walls is analyzed and compared in terms of various parameters such as force–deformation curve, energy dissipation, stiffness degradation, deformation ductility factor, response modification factor, and seismic performance levels, as well as rocking, in-plane sliding, and out-of-plane movement. The results indicate that the use of confining elements significantly improves the lateral load capacity, elastic stiffness, and displacement ductility factor of the confined masonry wall in comparison to an unreinforced masonry wall by 102%, 66.67%, and 5.3%, respectively. Overall, the study concludes that the inclusion of confining elements enhances the seismic performance of the confined masonry wall under lateral loading.

Application of BST Surfaces in the Seismic Performance Evaluation of Piloti-type Buildings

Application of BST Surfaces in the Seismic Performance Evaluation of Piloti-type Buildings

Evaluation and comparison of seismic performance of industrially and traditionally constructed buildings in Iran, a case study of Yasooj

Modern construction methods such as industrial ones have significantly increased the speed of buildings construction. Although these new methods are widely used in some countries, but the fundamental question is about their reliability and efficiency, especially in term of their seismic performance in comparison to the traditional construction methods. In this study, the seismic performance of constructed buildings using industrial construction methods is compared to the typical buildings in Iran. Besides, as main innovation, by defining building industrialization index, the economics of each structure has been also evaluated and the effect of this index on the structural performance has been studied. To this purpose, by conducting statistical studies on existing buildings, their information has been collected and three types of nonlinear finite element models including: eccentric steel braced frame, buckling restrained braced frame and tunnel formwork reinforced concrete shear wall have been prepared and compared. The near field earthquakes records have been used for nonlinear incremental dynamic analysis to obtain the corresponding fragility curves. The results showed that the tunnel formwork RC shear wall and buckling restrained braced frames, in addition to being more economical, also have more reliable collapse fragility curves and present better performance than the typical eccentric braced frames as they have a higher building industrialization index than the third structural system, respectively. Therefore, the modern buildings constructed by industrial methods have a lower casualty and economic risk due to the better seismic behavior compared to typical and traditional buildings.

Shaking table test of fully assembled precast concrete shear wall substructure with tooth groove connection and vertical reinforcement lapping in reserved hole

In this paper, an innovative fully assembled precast concrete shear wall structural system with tooth groove connection and vertical reinforcement lapping in reserved hole was proposed, and the constructional requirements and joint assembly process were elaborated in detail. Based on the similarity theory, a 1/2 scaled fully assembled precast shear wall substructure was designed and manufactured. The damage mode, dynamic characteristics, acceleration response, displacement response, seismic action response, inter-storey shear response and strain response of the fully assembled precast concrete shear wall substructure with tooth groove connection and vertical reinforcement lapping in reserved hole under the different earthquake excitations were comprehensively analyzed by shaking table test, and the connection performance and seismic performance of the substructure in high intensity areas were investigated. The research results showed that the cracks at the horizontal joint of the 1st floor were completely penetrated, accompanied by slight concrete spalling, the 1st floor shear wall perpendicular to the input direction of seismic excitation was slightly uplifted, and there was no obvious damage in other parts. Overall, the tooth groove connection and vertical reinforcement lapping in reserved hole was reliable. Besides, the dynamic characteristics and seismic response of the substructure were consistent with the three-stage test phenomena. The acceleration amplification factor, storey displacement, seismic action increased with the increase of the height of the substructure and the excitation of PGA. When the excitation of PGA = 0.638 g, the maximum inter-storey drift was 1/213, which was in line with the plastic limit of 1/120. On the whole, the integrity of the substructure remained good and there was no danger of collapse. Finally, a comprehensive seismic performance evaluation method suitable for fully assembled precast concrete shear wall substructure with tooth groove connection and vertical reinforcement lapping in reserved hole was proposed with inter-storey drift and damage index as quantitative indicators.

Verification of a stochastic dynamic analysis method by shaking table tests of a slope retaining system

Various sources of uncertainty can greatly affect the seismic responses and seismic reliability of slope retaining systems. Many studies have observed and highlighted that ignoring the effect of uncertainties, especially the randomness of ground motions, would cause an inaccurate evaluation of seismic performance of slope retaining system. It is thus of great significance to employ the stochastic dynamic analysis method to quantify these uncertainties and corresponding effect. A recently developed stochastic dynamic analysis method, namely probability density evolution method (PDEM), have been proposed for the stochastic seismic responses analysis of geotechnical engineering. Although its efficiency and accuracy have already been proved by numerical cases, its feasibility and accuracy has not been verified from the experimental perspective, and its application in the stochastic seismic responses analysis using the field monitor data and experiment results in geotechnical engineering has not yet been studied. In the present study, a hard-strength rock slope model reinforced by pile-anchor structures is firstly constructed for the repeating shaking under a series of ground motions. A set of fully non-stationary stochastic ground motions are generated to quantify the randomness of input ground motions. Then, the stochastic seismic responses of the slope retaining system, including acceleration responses, amplification effect and earth pressure along pile-anchor structures, are analyzed and compared by the PDEM and various assumed probabilistic distribution models to illustrate the feasibility and accuracy of PDEM from the experimental perspective. The results demonstrate that the PDEM can obtain relatively more accurate stochastic seismic response results, and can also be used to analyze the experimental data from the probabilistic perspective.

Seismic performance evaluation of a tall building with dual lateral system consisting of moment frames and tuned mass dampers

Seismic performance evaluation of a tall building with dual lateral system consisting of moment frames and tuned mass dampers