钢结构建筑的震害及其成因探析

本文根据国内外地震中钢结构建筑的破坏现象,研究震害产生原因,同时结合日本阪神地震中钢结构建筑的典型震害,列举出各种震害原因,提出了钢结构建筑抗震设计与施工要点,以避免类似震害的再次发生.     

汶川地震震害调查及分析

通过对多层砖混结构、框架结构、底框结构、单层工业厂房、钢结构等结构形式的建筑物在四川汶川地震中的震害调查,分析其破坏机理,并给出了一些设计建议。     

框架建筑砌体结构震害调查及原因浅析——以汶川震后漩口中学为例

漩口中学位于汶川地震中极震区映秀镇,系2008年地震遗址。本文主要对该校的框架建筑中的砌体结构震害展开调查,粗略分析了砌体结构的倒塌形式,给出了影响框架建筑砌体结构倒塌形式的原因,总结出框架建筑砌体结构在震中破坏的几种表现形式。     

底框架砌体房屋震害分析

底框架房屋是经济欠发达地区常采用的一种结构形式,它在历次地震中震害尤为突出。文章根据汶川地震房屋震害调查资料,总结该类房屋在地震中的震害规律,分析了震害产生的原因。对如何提高底框架房屋抗震性能提出若干建议,为该类房屋的设计及加固改造提供参考。     

汶川地震中部分建筑构件破坏的探讨

以汶川特大地震为出发点,通过整理地震灾区的震害资料,分析了大量房屋建筑的倒塌破坏情况,总结了建筑构件震害的破坏机理及抗震计算措施,从而进一步完善建筑物抗震设计。     

台湾9.21大地震多层框架结构震害特点和经验

1999年 9月 2 1日 ,我国台湾省发生了Ｍ7 3级的大地震。这次地震的特点是地震十分强烈、余震次数多、波及范围广、震害严重。根据震害统计 ,在这次大地震中多层钢筋混凝土框架房屋的破坏占很大比重 ,且震害资料十分丰富。本文试图对该类房屋的破坏现象和破坏机理作一初步探讨。     

汶川地震都江堰城区建筑震害调查分析

通过对都江堰城区建筑震害现场的调查,分析了框架结构、砌体结构、底框-上部砌体结构、文物保护建筑等各种常见结构在汶川地震时的破坏形态、破坏原因,对防震缝、楼梯间、屋面突出小塔楼也给出了典型的震害实例,提出了设计和施工中存在的技术问题,为总结抗建筑结构抗震经验和教训,提高设计和施工水平提供依据。     

西安市汶川地震震害调查与分析

笔者全程参与了西安市汶川地震震害调查,通过对西安市的各类建筑工程在汶川地震后的震害调研、现场考察,收集了大量建筑结构震害资料,对钢筋混凝土框架结构、砖混结构、底框砖混等不同类型的结构震害特征进行了归纳与总结。虽然西安市距离本次地震震中在600公里以上,但是一些建筑也出现了明显的破坏,本文对西安市在汶川特大地震中的建筑破坏受损原因作了初步分析,借以发现其中存在的问题和不足,为今后同类型结构和用途的工程项目抗震和有关规范的修订提供参考,同时也是西安市汶川地震震后总结非常重要的资料。     

汶川5．12,大地震建筑物震害分析

在汶川地震三周年之际,笔者一行再次来到映秀镇重灾区。通过对地震中建筑物震害的调查,结合现场图片,针对不同建筑结构类型所造成建筑物破坏或倒塌的原因,进行了初步分析。并建议了减轻建筑物震害的有关对策,为今后建筑抗震设计提供有益参考。     

日本阪神地震中的钢结构震害

本文对日本阪神地震中的钢结构震害,包括:罕见的两种破坏现象,厚壁柱子脆断和多层房屋中间层整层被摧毁;以及设计不合理和施工、焊接不良;焊接金属热影响区引起的破坏;大跨度空间结构出现的破坏等方面,作了全面简要介绍,并结合震害实况提供了初步分析。特供我国钢结构同行了解与进一步研究时参考。     

Risk-based decision support for seismic rehabilitation of structures

This study presents a risk-based decision support framework for seismic retrofit of building structures where the decision criterion is to minimize the sum of the cost required for the rehabilitation and the expected seismic loss over a specified time period. Probabilistic seismic hazard model (PSHM) and probabilistic seismic demand model (PSDM) are utilized for manipulation of the uncertainty propagation from the seismic hazard to the structural damage. A mathematical formula is then developed for probabilistic estimation of the seismic damage and losses over a specified time period. The analysis procedure is developed such that the effect of the different configurations of the decision inputs can be promptly observed. The proposed procedure is demonstrated by performing a decision analysis for a hypothetical RC building structure for determination of the optimal level of seismic rehabilitation using steel bracings.     

Special braced stairs versus typical braced frames. New architectural-structural-seismic approach to stair design

This paper presents a new approach to the project of steel buildings, mainly focused on the architectural, structural, and seismic design of stairs. The objective is to design a structural stair system capable of controlling seismic damage and contributing to the bracing system of the building. The article begins with a review of the seismic standard (ATC, FEMA, and EC8) on which the current design criteria for new buildings with stairs are based. The research is based on two spatial building models (A–B) with the same bracing elements but placed differently. Reference Model A follows classical design approaches. It means, stairs are considered nonstructural elements that do not influence the seismic behavior of the building. This structure corresponds to typical braced frames (IV-CBF and EBF) according to EC8. Model B includes a stair system designed to help control the effects of inter-story drifts and inertia forces. In this case, the same bracing elements of Model A were integrated into the stair structure of Model B. A comparative seismic behavior analysis of typically braced frames (A) versus specially braced stairs (B) is presented. The research was based on the static nonlinear (pushover) analysis and the capacity spectrum method (ATC-40) according to the seismic performance levels (FEMA) and damage limitation (EC8). Finally, the braced stairs was verified via nonlinear time-history analysis in order to better capture the structural safety of the evacuation routes and their influence on the behavior of the building. This deterministic analysis of the braced stairs verified satisfactory results compared to reference bracing systems.     

极罕遇地震作用下建筑结构一致风险抗倒塌设计方法研究

结合当前国际上以“抗倒塌”为目标进行地震动参数区划和以“一致倒塌风险”为设防目标进行结构抗震设计的发展趋势,针对我国现行建筑抗震设计规范体系中抗倒塌能力评估的局限性,建议了四种一致风险抗倒塌设计方法,详细介绍了四种方法的评价指标与计算过程。考虑极罕遇地震作用,基于极罕遇地震一致风险谱对地震动记录进行了挑选与调幅。以RC框-剪结构作为典型案例,采用四种抗倒塌设计方法进行验算,结果表明：同时考虑地震危险性与结构不确定性影响的全概率方法验算未通过,其余验算方法均通过,这说明了忽略结构所在场地危险性影响会造成结构倒塌性能评估的不准确性,未考虑结构体系多种不确定性影响会高估结构的抗倒塌性能,因此有必要推行“一致风险”的结构设计理念。     

Hysteretic model for steel energy dissipation devices and evaluation of a minimal-damage seismic design approach for steel buildings

This paper evaluates an alternative seismic design approach for steel structures that concentrates damage in easy-to-replace steel energy dissipation devices and protects the main structural members from yielding with capacity design rules. This approach can reduce damage repair costs and downtime, and, can be further enhanced by using rate-dependent dampers in parallel to steel devices to achieve drift reduction and protection of drift-sensitive non-structural elements. A model for steel energy dissipation devices is proposed and calibrated against experimental results. In particular, the Bouc-Wen model is modified to capture the combined kinematic and isotropic hardening in the hysteresis of steel devices. The model is found able to accurately predict the experimentally obtained hysteresis and is implemented in the OpenSees software for use in seismic response analysis. A simplified seismic design procedure is proposed and used to design a prototype steel building equipped with steel devices and viscous dampers according to explicitly defined minimal-damage performance objectives. Seismic analyses results indicate the accuracy of the design procedure and confirm that the building is able to achieve immediate occupancy under the design seismic action and rapid return to occupancy under the maximum considered seismic action. The same building is designed as a conventional steel MRF according to EC8. Results of seismic analyses show that repair of damage in the main structural members of the conventional MRF may not be financially viable in the aftermath of the design and maximum considered earthquakes.     

Reliability-based service life assessment for deteriorating reinforced concrete buildings considering the effect of cumulative damage

Most engineering systems used in maintenance strategies must consider deterioration and seismic structural damage. To identify the effects of deterioration and earthquakes simultaneously on structural performance, this study applies an integral simulation method. Compared with that of previous studies, the feature of the proposed method is its analysis of the time-dependent structural capacity of a deteriorating reinforced concrete (RC) building and the simulation of life-cycle earthquake events within a specified service period, while considering cumulative damage induced by deterioration and earthquakes. In addition, the proposed assessment method is applied to derive the reliability-based service life of a deteriorating RC building located in a region with high seismic hazard. Briefly, for deteriorating RC buildings, the proposed reliability-based service life assessment method provides useful information related to maintenance based on both serviceability and safety.     

Seismic analysis of steel structures considering damage cumulation

The research on the development of a reliable analytical model for seismic analysis of steel structures is presented. The non-linear damage cumulation hysteretic model incorporating the deterioration of stiffness, strength and strain hardening for structural steel is proposed and validated. The complete loading history, energy dissipation and the effect of the maximum plastic strain are taken into account in the model. The constants in the model are determined from regression analysis of experimental results of simple standard tensile and cyclic tests. Finite element formulations for beam and structural solid element considering the damage cumulation are derived. A computer program capable of calculating the hysteretic model of steel members, predicting the damage state and crack initiation, and carrying out non-linear time history seismic analysis of steel structures is developed. Solutions obtained from the model are in good agreement with experimental results. It was demonstrated that the damage cumulation effect is considerable and important in structural seismic analysis.     

考虑多重不确定性的我国多层#br# 冷成型钢结构地震风险评估

准确评估建筑结构的地震风险是实现其性能化抗震设计的重要组成部分。冷成型钢结构体系作为绿色和工业化建筑的典型代表,却鲜有针对于我国的地震风险评估研究。文章旨在分析和评估多层冷成型钢结构抗震分析所涉及的多重不确定性因素,进而定量评估该类结构在我国的地震风险。文章设计1栋八度抗震设防的6层冷成型钢结构,基于经过振动台验证的简化数值分析方法建立结构的简化数值模型,定量求解结构的多重不确定性因素和在使用周期内(50年)的地震风险。研究结果表明：由于我国一些地区的地震危险性形状系数较大,在考虑多重不确定性后,结构的破坏概率显著提高,50年使用周期内倒塌概率的增幅达到10倍以上;算例结构在50年使用周期内基本满足“小震不坏、中震可修、大震不倒”的抗震设防要求,对于个别特殊区域应适当控制结构发生轻微破坏的概率。此外,文章建议应全面考虑多重不确定对冷成型钢结构地震风险的影响,对不确定性参数的取值和地震风险的计算方法可提供借鉴。     

汶川地震中底框和框架结构的震害分析

通过对西南地区底框和框架结构在汶川地震后的震害调研,收集了大量建筑结构震害资料,对底框砖混结构、钢筋混凝土框架结构两类结构的震害特征进行了统计,分析了建筑结构震害机理,以及初步探讨了地震区建筑结构选型和抗震措施问题,从而优化建筑结构抗震设计。     

Pseudo-dynamic testing of hybrid frame with steel beams bolted to CFT columns

This paper presents an experimental study on seismic behavior of a composite structural frame system consisting of concrete filled steel tube columns and steel beams with bolted endplate connections. Based on current seismic provisions and previous research, a ten-story prototype building was designed. Analytical models were developed to predict the elasto-plastic behavior of the prototype frame under a series of ground motion records. A four-seventh scale sub-structure model consisting of two stories and one and half span was constructed and subjected to simulated seismic excitations using pseudo-dynamic hybrid testing method. Results from the tests indicate that the model behavior under the simulated seismic loading was consistent with the expected performances analyzed for different earthquake hazard levels. Finally, quasi-static test and pushover test were also conducted to identify the ultimate failure mode of the testing model. The study shows that the proposed system can offer appropriate strength and adequate ductility required for seismic design.     

基于耗能差指数和SIR模型的#br# 结构易损性及可恢复能力评估

传统结构地震易损性中结构地震响应指标对损伤反映不充分,且无法为结构震后可恢复性评估提供准确的初始损伤指标。针对上述不足和结构地震可恢复能力评估的需求,提出运用基于弹塑性耗能差的损伤指数进行结构地震易损性评价的方法。建立可推演出指定地震动强度和超越概率下的损伤指数的计算方法。利用SIR模型能够描述系统损伤和恢复动态演变过程的特点,提出基于该模型的单体建筑结构和区域建筑群的性能水平恢复函数模型及结构的恢复能力计算方法,从而表征建筑结构群体在地震激励下的“直接损伤 间接损伤 恢复”全过程。以单体结构和区域结构为算例进行易损性分析和震后可恢复性评估,结果表明：基于弹塑性耗能差的损伤指数具有真实可靠和机理明确的特点,在离散性和相关性方面均优于传统指标。SIR可恢复性能评估模型较常用恢复函数模型更为精准,简单高效且适合推广到区域建筑集群体当中,是对现有区域恢复性能评估框架的有益补充。