Simplified stiffness-based approach for seismic performance evaluation of moment-resisting frame

Based on the concept of stiffness degradation, a damage index of the whole frame and the storey is proposed for the frame seismic performance evaluation. The index is compatible with the non-linear static analysis （e. g. the pushover analysis）, and the structural damage is considered via plastic hinges. Simultaneously, a practical approach is developed to obtain the relationships between the proposed index and earthquake intensities based on the capacity spectrum method. The proposed index is then illustrated through two low-rise reinforced concrete frames, and it is also compared with some other indices. The results indicate that the proposed index is on the safe side and not sensitive to the lateral load pattern. The storey index is helpful to reflect the storey damage and to uncover the position of the weak storey. Finally, the relationship between performance levels and damage index values is also proposed through statistical analysis for the performance-based seismic evaluation.

Seismic risk evaluation for a planning mountain tunnel using improved analytical hierarchy process based on extension theory

Seismic risk evaluation(SRE) in early stages(e.g., project planning and preliminary design)for a mountain tunnel located in seismic areas has the same importance as that in final stages(e.g.,performance-based design, structural analysis, and optimization). SRE for planning mountain tunnels bridges the gap between the planning on the macro level and the design/analysis on the micro level regarding the risk management of infrastructural systems. A transition from subjective or qualitative description to objective or quantitative quantification of seismic risk is aimed to improve the seismic behavior of the mountain tunnel and thus reduce the associated seismic risk. A new method of systematic SRE for the planning mountain tunnel was presented herein. The method employs extension theory(ET)and an ET-based improved analytical hierarchy process. Additionally, a new risk-classification criterion is proposed to classify and quantify the seismic risk for a planning mountain tunnel. This SRE method is applied to a mountain tunnel in southwest China, using the extension model based on matter element theory and dependent function operation.The reasonability and flexibility of the SRE method for application to the mountain tunnel are illustrated.According to different seismic risk levels and classification criteria, methods and measures for improving the seismic design are proposed, which can reduce the seismic risk and provide a frame of reference for elaborate seismic design.

Seismic performance evaluation of steel frame-steel plate shear walls system based on the capacity spectrum method

This paper presents some methods that the standard acceleration design response spectra derived from the present China code for seismic design of buildings are transformed into the seismic demand spectra, and that the base shear force-roof displacement curve of structure is converted to the capacity spectrum of an equivalent single-degree-of-freedom （SDOF） system. The capacity spectrum method （CSM） is programmed by means of MATLABT.0 computer language. A dual lateral force resisting system of 10-story steel frame-steel plate shear walls （SPSW） is designed according to the corresponding China design codes. The base shear force-roof displacement curve of structure subjected to the monotonic increasing lateral inverse triangular load is obtained by applying the equivalent strip model to stimulate SPSW and by using the finite element analysis software SAP2000 to make Pushover analysis. The seismic performance of this dual system subjected to three different conditions, i.e. the 8-intensity frequently occurred earthquake, fortification earthquake and seldom occurred earthquake, is evaluated by CSM program. The excessive safety of steel frame-SPSW system designed according to the present China design codes is pointed out and a new design method is suggested.

Seismic demand evaluation of medium ductility RC moment frames using nonlinear procedures

Performance-based earthquake engineering is a recent focus of research that has resulted in widely developed design methodologies due to its ability to realistically simulate structural response characteristics. Precise prediction of seismic demands is a key component of performance-based design methodologies. This paper presents a seismic demand evaluation of reinforced concrete moment frames with medium ductility. The accuracy of utilizing simplified nonlinear static analysis is assessed by comparison against the results of time history analysis on a number of frames. Displacement profiles, drift demand and maximum plastic rotation were computed to assess seismic demands. Estimated seismic demands were compared to acceptance criteria in FEMA 356. The results indicate that these frames have sufficient capacity to resist interstory drifts that are greater than the limit value.

Research on the effect estimation of seismic safety evaluation

Seismic safety evaluation is a basic work for determining the seismic resistance requirements of major construc-tion projects. The effect, especially the economic effect of the seismic safety evaluation has been generally con-cerned. The paper gives a model for estimating the effect of seismic safety evaluation and calculates roughly the economic effect of seismic safety evaluation with some examples.

A“Three-index”Seismic Performance Evaluation Method Based on Sino-US Seismic Code

The Code for Seismic Design of Buildings(GB50011-2010)in 2016 and the method of seismic performance-based design for high-rise buildings in the Guide for Performance-based Design of High-Rise Buildings(TBI2017)are compared.In view of the characteristics and limitations of the seismic performance index set by the Sino-US seismic code,a“three-index”performance index system and evaluation process considering the displacement angle of the structural interlayer,the plastic damage degree of components and the plastic strain of material is put forward;combining the example of time-history analysis of a out-of-code high-rise building under the rare earthquakes is verified.The results show that the method of seismic performance evaluation by using deformation control index in Sino-US seismic code is relatively simple;however,both are lacking in the setting of specific components and the whole structure level respectively.The"three-index"system can comprehensively and quantitatively evaluate the seismic performance of out-of-code high-rise buildings.

Active Tectonic Research for Seismic Safety Evaluation of Long-Line Engineering Sites in China

Long-line engineering sites usually have to pass through active tectonics, so the research of active tectonics is of great importance to seismic safety evaluation of this sort of site. In the paper, basing on the summarization and analysis of the requirements for seismic safety evaluation of long-line engineering site and the status quo of active tectonics research, we propose the focal points of active tectonics research for seismic safety evaluation of long-line engineering sites, including the research contents, technical targets and routes, and the submission of the achievements, etc. Finally, we make a preliminary analysis and discussion about the problems existing in the present-day active tectonics research for seismic safety evaluation of long-line engineering sites.

Evaluation of Regular Multistory Buildings Using IBC2009 Code and ESEE Regulations by Pushover Analysis Method

For structural design and assessment of reinforced concrete members, the nonlinear analysis has become an important tool. The purpose of the pushover analysis is to assess the structural performance by estimating the strength and deformation capacities using static, nonlinear analysis and comparing these capacities with the demands at the corresponding performance levels. This paper aims to compare the results given by IBC2009 code and ESEE regulations. In this paper, four RC frames having 5, 15, 20 and 30 storeys were designed for seismicity according to both the recently adopted seismic code in Abu Dhabi (IBC2009) and the ESEE regulations. A pushover analysis is carried out for these buildings using SAP2000 (Ver. 15) and the ultimate capacities of the buildings are established. The obtained pushover curves and plastic hinges distributions are used to compare between the IBC2009 code and ESEE regulations. The comparison showed that there was variation in the obtained results by the two codes and the buildings designed by IBC2009 code were more vulnerable.

Analysis of seismic disaster failure mechanism and dam-break simulation of high arch dam

Based on a Chinese national high arch dam located in a meizoseismal region, a nonlinear numerical analysis model of the damage and failure process of a dam-foundation system is established by employing a 3-D deformable distinct element code(3DEC) and its re-development functions. The proposed analysis model considers the dam-foundation-reservoir coupling effect, infl uence of nonlinear contact in the opening and closing of the dam seam surface and abutment rock joints during strong earthquakes, and radiation damping of far fi eld energy dissipation according to the actual workability state of an arch dam. A safety assessment method and safety evaluation criteria is developed to better understand the arch dam system disaster process from local damage to ultimate failure. The dynamic characteristics, disaster mechanism, limit bearing capacity and the entire failure process of a high arch dam under a strong earthquake are then analyzed. Further, the seismic safety of the arch dam is evaluated according to the proposed evaluation criteria and safety assessment method. As a result, some useful conclusions are obtained for some aspects of the disaster mechanism and failure process of an arch dam. The analysis method and conclusions may be useful in engineering practice.

Large, moderate, small earthquakes and seismic fortification criterion

This paper discusses the relation between two-step seismic design and the standard of probability of exceedance, and the relation of three-levels seismic ground motion parameters given by probability method and comprehensive probability method. The relative size relations of the ground motions with 2%, 10%, 63% probability of exceedance in 50 years, namely large earthquake, moderate earthquake, and small earthquake, are discussed through a practical example of seismic hazard analysis. The methods to determine seismic fortification criterion are discussed.

Occurrence Probability Evaluation of the Maximum Potential Earthquake on the Faults in Zhengzhou City

According to the results of estimation of the maximum potential earthquake in the project of ＂The Active Fault Detection and Seismic Risk Evaluation （Phase H） of Zhengzhou City＂, the near east-west trending Laoyachen fault and Shangjie fault are developed in the urban area. The Laoyachen fault was not active in the Quaternary, but the Shangjie fault may have the potential of generating M5.0 - 5.5 earthquakes. In order to get the probability of occurrence of maximum potential earthquakes, we delineate the statistical areas and the potential source areas and calculate the seismicity parameters and the space distribution functions. Our study shows that the probability of occurrence of an earthquake with M〉 5.0 on the faults in Zhengzhou city is 6% in the next 50 years and 11% in the next 100 years.

The Principle and Method for Delineation of Potential Seismic Sources in Northwest Yunnan

Based on the collection and analysis of achievements of other scholars, and by consulting the results of seismic safety evaluation of engineering sites and field surveys of recent years, the seismotectonic indicators are determined for northwest Yunnan and its vicinity, and then potential seismic sources are further delineated. In practice, the following principles are applied: for areas with strong historical earthquakes, the recurrence principle is used to determine the upper bound magnitude; for areas with distinct seismogenic structure but no historical strong earthquake records, the tectonic analogy principle is used in the light of the size and activity behavior of the structure; for areas where the segmentation of the active fault is well studied, the potential sources will be demarcated more precisely; and for areas with buried fault, the seismicity pattern and geophysical abnormity are used to determine the direction of the major axis of the potential seismic source.

Pushover analysis of reinforced concrete frames considering shear failure at beam-column joints

Since most current seismic capacity evaluations of reinforced concrete （RC） frame structures are implemented by either static pushover analysis （PA） or dynamic time history analysis, with diverse settings of the plastic hinges （PHs） on such main structural components as columns, beams and walls, the complex behavior of shear failure at beam-column joints （BCJs） during major earthquakes is commonly neglected. This study proposes new nonlinear PA procedures that consider shear failure at BCJs and seek to assess the actual damage to RC structures. Based on the specifications of FEMA-356, a simplified joint model composed of two nonlinear cross struts placed diagonally over the location of the plastic hinge is established, allowing a sophisticated PA to be performed. To verify the validity of this method, the analytical results for the capacity curves and the failure mechanism derived from three different full-size RC frames are compared with the experimental measurements. By considering shear failure at BCJs, the proposed nonlinear analytical procedures can be used to estimate the structural behavior of RC frames, including seismic capacity and the progressive failure sequence of joints, in a precise and effective manner.

A phased approach to enable hybrid simulation of complex structures

Hybrid simulation has been shown to be a cost-effective approach for assessing the seismic performance of structures. In hybrid simulation,critical parts of a structure are physically tested,while the remaining portions of the system are concurrently simulated computationally,typically using a finite element model. This combination is realized through a numerical time-integration scheme,which allows for investigation of full system-level responses of a structure in a cost-effective manner. However,conducting hybrid simulation of complex structures within large-scale testing facilities presents significant challenges. For example,the chosen modeling scheme may create numerical inaccuracies or even result in unstable simulations; the displacement and force capacity of the experimental system can be exceeded; and a hybrid test may be terminated due to poor communication between modules(e.g.,loading controllers,data acquisition systems,simulation coordinator). These problems can cause the simulation to stop suddenly,and in some cases can even result in damage to the experimental specimens; the end result can be failure of the entire experiment. This study proposes a phased approach to hybrid simulation that can validate all of the hybrid simulation components and ensure the integrity largescale hybrid simulation. In this approach,a series of hybrid simulations employing numerical components and small-scale experimental components are examined to establish this preparedness for the large-scale experiment. This validation program is incorporated into an existing,mature hybrid simulation framework,which is currently utilized in the Multi-Axial Full-Scale Sub-Structuring Testing and Simulation(MUST-SIM) facility of the George E. Brown Network for Earthquake Engineering Simulation(NEES) equipment site at the University of Illinois at Urbana-Champaign. A hybrid simulation of a four-span curved bridge is presented as an example,in which three piers are experimentally controlled in a total of 18 degrees of freedom(DOFs). This simulation illustrates the effectiveness of the phased approach presented in this paper.