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1.
Seismic behavior of asymmetric RC wall buildings: principles and new deformation‐based design method
The seismic design of multi‐story buildings asymmetric in plan yet regular in elevation and stiffened with ductile RC structural walls is addressed. A realistic modeling of the non‐linear ductile behavior of the RC walls is considered in combination with the characteristics of the dynamic torsional response of asymmetric buildings. Design criteria such as the determination of the system ductility, taking into account the location and ductility demand of the RC walls, the story‐drift demand at the softer (most displaced) edge of the building under the design earthquake, the allowable ductility (ultimate limit state) and the allowable story‐drift (performance goals) are discussed. The definition of an eccentricity of the earthquake‐equivalent lateral force is proposed and used to determine the effective displacement profile of the building yet not the strength distribution under the design earthquake. Furthermore, an appropriate procedure is proposed to calculate the fundamental frequency and the earthquake‐equivalent lateral force. A new deformation‐based seismic design method taking into account the characteristics of the dynamic torsional response, the ductility of the RC walls, the system ductility and the story‐drift at the softer (most displaced) edge of the building is presented and illustrated with an example of seismic design of a multi‐story asymmetric RC wall building. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
2.
A simplified design procedure (SDP) for preliminary seismic design of frame buildings with structural dampers is presented. The SDP uses elastic‐static analysis and is applicable to structural dampers made from viscoelastic (VE) or high‐damping elastomeric materials. The behaviour of typical VE materials and high‐damping elastomeric materials is often non‐linear, and the SDP idealizes these materials as linear VE materials. With this idealization, structures with VE or high‐damping elastomeric dampers can be designed and analysed using methods based on linear VE theory. As an example, a retrofit design for a typical non‐ductile reinforced concrete (RC) frame building using high‐damping elastomeric dampers is developed using the SDP. To validate the SDP, results from non‐linear dynamic time history analyses (NDTHA) are presented. Results from NDTHA demonstrate that the SDP estimates the seismic response with sufficient accuracy for design. It is shown that a non‐ductile RC frame building can be retrofit with high‐damping elastomeric dampers to remain essentially elastic under the design basis earthquake (DBE). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
3.
Seismic safety of low ductility structures used in Spain 总被引：1，自引：0，他引：1
The most important aspects of the design, seismic damage evaluation and safety assessment of structures with low ductility
like waffle slabs buildings or flat beams framed buildings are examined in this work. These reinforced concrete structural
typologies are the most used in Spain for new buildings but many seismic codes do not recommend them in seismic areas. Their
expected seismic performance and safety are evaluated herein by means of incremental non linear structural analysis (pushover
analysis) and incremental dynamic analysis which provides capacity curves allowing evaluating their seismic behavior. The
seismic hazard is described by means of the reduced 5% damped elastic response spectrum of the Spanish seismic design code.
The most important results of the study are the fragility curves calculated for the mentioned building types, which allow
obtaining the probability of different damage states of the structures as well as damage probability matrices. The results,
which show high vulnerability of the studied low ductility building classes, are compared with those corresponding to ductile
framed structures. 相似文献
4.
Hemchandra Chaulagain Hugo Rodrigues Enrico Spacone Ramesh Guragain Radhakrishna Mallik Humberto Varum 《地震工程与工程振动(英文版)》2014,13(3):455-470
Most current seismic design includes the nonlinear response of a structure through a response reduction factor(R). This allows the designer to use a linear elastic force-based approach while accounting for nonlinear behavior and deformation limits. In fact, the response reduction factor is used in modern seismic codes to scale down the elastic response of a structure. This study focuses on estimating the actual ‘R' value for engineered design/construction of reinforced concrete(RC) buildings in Kathmandu valley. The ductility and overstrength of representative RC buildings in Kathmandu are investigated. Nonlinear pushover analysis was performed on structural models in order to evaluate the seismic performance of buildings. Twelve representative engineered irregular buildings with a variety of characteristics located in the Kathmandu valley were selected and studied. Furthermore, the effects of overstrength on the ductility factor, beam column capacity ratio on the building ductility, and load path on the response reduction factor, are examined. Finally, the results are further analyzed and compared with different structural parameters of the buildings. 相似文献
5.
Evaluation of collapse resistance of RC frame structures for Chinese schools in seismic design categories B and C 总被引：3，自引：2，他引：1
According to the Code for Seismic Design of Buildings (GB50011-2001), ten typical reinforced concrete (RC) frame structures, used as school classroom buildings, are designed with different seismic fortification intensities (SFIs) (SFI=6 to 8.5) and different seismic design categories (SDCs) (SDC=B and C). The collapse resistance of the frames with SDC=B and C in terms of collapse fragility curves are quantitatively evaluated and compared via incremental dynamic analysis (IDA). The results show that the coll... 相似文献
6.
A composite shear wall concept based on concrete filled steel tube （CFST） columns and steel plate （SP） deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements： CFST columns; SP deep beams; and reinforced concrete （RC） strips. The RC strips are intended to allow the core structural elements - the CFST columns and SP deep beams - to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures. 相似文献
7.
综述了用于提高填充墙钢筋混凝土(RC)框架结构抗震性能和改善结构损伤模式的几类加固措施,从工艺、加固效果和破坏形式3个角度进行了分析。在建筑结构设计过程中,填充墙通常被视为一种典型的脆性非均质非结构构件,忽视了填充墙与RC框架之间的相互作用。地震调查报告表明,在结构遭受地震作用时,填充墙通常先于钢筋混凝土框架发生破坏,未经合理设计的填充墙RC框架结构将在地震作用下产生严重不良后果。试验结果和数值模拟分析结果证明,砌块的强度越低、砂浆的强度越高,结构的承载能力和刚度退化越慢、耗能能力越好。文中根据目前已有的建筑材料改性试验结果,从改性机理出发,分析了一系列有利于提高结构抗震性能的新型材料,并对结构的设计方案进行了探讨。 相似文献
8.
Strong near-fault ground motion, usually caused by the fault-rupture and characterized by a pulse-like velocity- wave form, often causes dramatic instantaneous seismic energy (Jadhav and Jangid 2006). Some reinforced concrete (RC) bridge columns, even those built according to ductile design principles, were damaged in the 1999 Chi-Chi earthquake. Thus, it is very important to evaluate the seismic response of a RC bridge column to improve its seismic design and prevent future damage. Nonlinear time history analysis using step-by-step integration is capable of tracing the dynamic response of a structure during the entire vibration period and is able to accommodate the pulsing wave form. However, the accuracy of the numerical results is very sensitive to the modeling of the nonlinear load-deformation relationship of the structural member. FEMA 273 and ATC-40 provide the modeling parameters for structural nonlinear analyses of RC beams and RC columns. They use three parameters to define the plastic rotation angles and a residual strength ratio to describe the nonlinear load- deformation relationship of an RC member. Structural nonlinear analyses are performed based on these parameters. This method provides a convenient way to obtain the nonlinear seismic responses of RC structures. However, the accuracy of the numerical solutions might be further improved. For this purpose, results from a previous study on modeling of the static pushover analyses for RC bridge columns (Sung et al. 2005) is adopted for the nonlinear time history analysis presented herein to evaluate the structural responses excited by a near-fault ground motion. To ensure the reliability of this approach, the numerical results were compared to experimental results. The results confirm that the proposed approach is valid. 相似文献
9.
Non‐ductile reinforced concrete buildings represent a prevalent construction type found in many parts of the world. Due to the seismic vulnerability of such buildings, in areas of high seismic activity non‐ductile reinforced concrete buildings pose a significant threat to the safety of the occupants and damage to such structures can result in large financial losses. This paper introduces advanced analytical models that can be used to simulate the nonlinear dynamic response of these structural systems, including collapse. The state‐of‐the‐art loss simulation procedure developed for new buildings is extended to estimate the expected losses of existing non‐ductile concrete buildings considering their vulnerability to collapse. Three criteria for collapse, namely first component failure, side‐sway collapse, and gravity‐load collapse, are considered in determining the probability of collapse and the assessment of financial losses. A detailed example is presented using a seven‐story non‐ductile reinforced concrete frame building located in the Los Angeles, California. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
10.
Benjamín Westenenk Juan Carlos de la Llera Rosita Jünemann Matías A. Hube Juan José Besa Carl Lüders José Antonio Inaudi Rafael Riddell Rodrigo Jordán 《Bulletin of Earthquake Engineering》2013,11(1):69-91
Observed trends in the seismic performance of eight severely damaged reinforced concrete (RC) structures after the February 27, 2010, Chile earthquake are presented in this article. After a reconnaissance and surveying process conducted immediately after the earthquake, several aspects not conventionally considered in building design were observed in the field. Most of the considered structures showed extensive localized damage in walls of lower stories and first basements. Several factors indicate that damage was brittle, and occurred mainly in recent RC structures supported on soft soils with some degree of vertical and/or horizontal irregularity. Non-ductile behavior has been inferred due to the lack of evidence of spread damage in the structure, and the fact that very similar structural configurations existed nearby without apparent damage. Some key aspects in understanding the observed damage are: geographical orientation of the building, presence of vertical and horizontal irregularities, wall thickness and reinforcement detailing, and lack of sources for energy dissipation. Additionally, results of a building-code type analysis are presented for the 4 most critical buildings, and Demand/Capacity ratios are calculated and compared with the observed behavior. It is concluded that the design codes must be revised relative to wall design provisions. 相似文献
11.
隔震器与填充墙对建筑抗震性能有很大作用。为了探究填充墙布置形式及填充材料和隔震器协同作用对钢筋混凝土框架结构动力特性及抗震性能的影响,采用等效斜撑理论,对3种不同填充墙布置形式与隔震器协同作用的抗震系统方案进行对比分析,研究发现顶层不布置填充墙与隔震器协同抗震系统钢筋混凝土框架结构的抗震性能最佳。在此系统上分析了不同填充材料对钢筋混凝土框架结构抗震性能的影响,结果表明,加气混凝土砌块填充墙的钢筋混凝土框架结构抗震性能最好。 相似文献
12.
基于性能的既有钢筋混凝土建筑结构抗震评估与加固技术研究 总被引：2，自引：0，他引：2
根据我国现行的建筑结构抗震规范,无论是新建建筑结构的抗震设计还是既有建筑结构的抗震评估与加固,均通过小震弹性承载力计算 抗震延性构造措施来达到"小震不坏、中震可修、大震不倒"的抗震设防目标(对于不规则且具有明显薄弱部位的建筑结构还需要进行罕遇地震作用下的弹塑性层间变形验算)。对于抗震延性构造措施不满足现行规范的既有建筑结构的评估、改建、扩建,如果仅通过小震弹性的承载力计算,显然无法达到"大震不倒"的目标。本文通过引入国际上先进的基于性能的结构抗震思想,以结构层间位移和结构构件变形作为性能目标,从定量上解决了既有钢筋混凝土建筑结构的抗震评估与加固问题。 相似文献
13.
In order to develop new standards related to structures in seismic regions, a series of research programmes has been conducted
on slightly reinforced structural walls commonly used in France. Based on these researches, a method of design of such walls
submitted to a seismic action has been set up. This method used in the PS92 code differs from that used for ductile walls,
where a plastic hinge can develop at the base of the wall. The analysis is similar to the push over analysis presently given
in Eurocode 8. These various researches have confirmed the validity of the design concept developed for the PS92 code, on
one hand, and highlighted a number of phenomena linked to the non linear behaviour of reinforced concrete walls, on the other
hand. The present article aims at presenting a synthesis of the results obtained during these research programmes. 相似文献
14.
Revision of seismic design codes corresponding to building damagesin the “5.12” Wenchuan earthquake 总被引：1，自引：1，他引：0
Yayong Wang 《地震工程与工程振动(英文版)》2010,9(2):147-155
A large number of buildings were seriously damaged or collapsed in the "5.12" Wenchuan earthquake. Based on field surveys and studies of damage to different types of buildings, seismic design codes have been updated. This paper briefly summarizes some of the major revisions that have been incorporated into the "Standard for classification of seismic protection of building constructions GB50223-2008" and "Code for Seismic Design of Buildings GB50011-2001." The definition of seismic fortification class for buildings has been revisited, and as a result, the seismic classifications for schools, hospitals and other buildings that hold large populations such as evacuation shelters and information centers have been upgraded in the GB50223-2008 Code. The main aspects of the revised GB50011-2001 code include: (a) modification of the seismic intensity specified for the Provinces of Sichuan, Shanxi and Gansu; (b) basic conceptual design for retaining walls and building foundations in mountainous areas; (c) regularity of building configuration; (d) integration of masonry structures and precast RC floors; (e) requirements for calculating and detailing stair shafts; and (f) limiting the use of single-bay RC frame structures. Some significant examples of damage in the epicenter areas are provided as a reference in the discussion on the consequences of collapse, the importance of duplicate structural systems, and the integration of RC and masonry structures. 相似文献
15.
This paper proposes a method for the estimation of the seismic energy demands of two-way asymmetric-plan buildings under bi-directional
ground excitations. The modal absorbed energies of asymmetric-plan buildings are estimated by using the three-degree-of-freedom
(3DOF) modal systems. The 3DOF modal system represents the two roof translations versus the two base shears and the roof rotation
versus the base torque relationships of each vibration mode of two-way asymmetric-plan buildings. Not only the total absorbed
energy but also the portions of the total absorbed energy contributed from translational and rotational deformations can be
respectively estimated. This study verifies the relationship between the signs of modal eccentricities and the trend of uneven
distribution of modal absorbed energy on floor-plan edges of asymmetric-plan buildings. The accuracy of the proposed method
was verified by analyzing one 3-storey and one 20-storey two-way asymmetric-plan buildings subjected to bi-directional ground
motions. The computational efficiency of the proposed method is confirmed by comparing the computation time with that required
by using the nonlinear response history analysis. 相似文献
16.
Seismic fragility assessment of RC frame structure designed according to modern Chinese code for seismic design of buildings 总被引：1，自引：0，他引：1
Following several damaging earthquakes in China,research has been devoted to find the causes of the collapse of reinforced concrete(RC) building sand studying the vulnerability of existing buildings.The Chinese Code for Seismic Design of Buildings(CCSDB) has evolved over time,however,there is still reported earthquake induced damage of newly designed RC buildings.Thus,to investigate modern Chinese seismic design code,three low-,mid-and high-rise RC frames were designed according to the 2010 CCSDB and the corresponding vulnerability curves were derived by computing a probabilistic seismic demand model(PSDM).The PSDM was computed by carrying out nonlinear time history analysis using thirty ground motions obtained from the Pacific Earthquake Engineering Research Center.Finally,the PSDM was used to generate fragility curves for immediate occupancy,significant damage,and collapse prevention damage levels.Results of the vulnerability assessment indicate that the seismic demands on the three different frames designed according to the 2010 CCSDB meet the seismic requirements and are almost in the same safety level. 相似文献
17.
Performance-Based Seismic Design is now widely recognized as the pre-eminent seismic design and assessment methodology for
building structures. In recognition of this, seismic codes may require that buildings achieve multiple performance objectives
such as withstanding moderate, yet frequently occurring earthquakes with minimal structural and non-structural damage, while
withstanding severe, but rare earthquakes without collapse and loss of life. These objectives are presumed to be satisfied
by some codes if the force-based design procedures are followed. This paper investigates the efficacy of the Eurocode 8 force-based
design provisions with respect to RC frame building design and expected seismic performance. Four, eight, and 16-storey moment
frame buildings were designed and analyzed using the code modal response spectrum analysis provisions. Non-linear time-history
analyses were subsequently performed to determine the simulated seismic response of the structures and to validate the Eurocode
8 force-based designs. The results indicate the design of flexural members in medium-to-long period structures is not significantly
influenced by the choice of effective member stiffness; however, calculated interstorey drift demands are significantly affected.
This finding was primarily attributed to the code’s enforcement of a minimum spectral ordinate on the design spectrum. Furthermore,
design storey forces and interstorey drift demand estimates (and therefore damage), obtained by application of the code force-based
design procedure varied substantially from those found through non-linear time-history analysis. Overall, the results suggest
that though the Eurocode 8 may yield life-safe designs, the seismic performance of frame buildings of the same type and ductility
class can be highly non-uniform. 相似文献
18.
汶川地震后绵竹、都江堰市房屋震害调查与分析 总被引：1，自引：0，他引：1
依据笔者在四川省绵竹市、都江堰市参加建设部组织的汶川地震震后房屋应急评估所取得的资料,对该次地震造成的建筑结构破坏进行了分析,从砖砌体结构、混凝土框架结构、构造问题以及设计与施工缺陷4个方面,论述了各种破坏的形态与成因,讨论了现行设计方法中存在的问题,提出了相应的改进建议。主要结论有：砌体结构的底层墙体强度不足、开间过大、形体复杂是导致其破坏的重要原因,在设计中,应适当提高砌体结构底层墙体的强度,控制房屋的开间,加强形体变化部位;砌体结构的窗下墙应作为连接墙肢的连梁考虑,可以将其设计成抗震设防的第一道防线;框架结构设计中,应考虑框架与填充墙的相互作用,考虑楼梯斜梁或斜板参与结构的整体受力;在现行规范要求的基础上,要适当增加框架柱的截面,节点附近的箍筋应采用焊接封闭箍或螺旋箍;应加强非结构构件的连接与锚固;对乡村房屋建设应予以监管,杜绝结构体系不明确的房屋出现。 相似文献
19.
The seismic evaluation of existing buildings is a more difficult task than the seismic design of new buildings. Non-linear
methods are needed if realistic results are to be obtained. However, the application to real complex structures of various
evaluation procedures, which have usually been tested on highly idealized structural models, is by no means straightforward.
In the paper, a practice-oriented procedure for the seismic evaluation of building structures, based on the N2 method, is
presented, together with the application of this method to an existing multi-storey reinforced concrete building. This building,
which is asymmetric in plan and irregular in elevation, consists of structural walls and frames. It was designed in 1962 for
gravity loads and a minimum horizontal loading (2% of the total weight). The main results presented in terms of the global
and local seismic demands are compared with the results of non-linear dynamic response-history analyses. As expected, the
structure would fail if subjected to the design seismic action according to Eurocode 8. The shear capacity of the structural
walls is the most critical. If the shear capacity of these elements was adequate, the structure would be able to survive the
design ground motion according to Eurocode 8, in spite of the very low level of design horizontal forces. The applied approach
proved to be a feasible tool for the seismic evaluation of complex structures. However, due to the large randomness and uncertainty
which are involved in the determination of both the seismic demand and the seismic capacity, only rough estimates of the seismic
behaviour of such structures can be obtained. 相似文献
20.
The opportunities provided by the use of fiber‐reinforced polymer (FRP) for the seismic retrofit of existing reinforced concrete (RC) structures were assessed on a full‐scale three‐story framed structure. The structure, designed only for gravity loads, was subjected to a bi‐directional pseudo‐dynamic (PsD) test at peak ground acceleration (PGA) equal to 0.20g at the ELSA Laboratory of the Joint Research Centre. The seismic deficiencies exhibited by the structure after the test were confirmed by post‐test assessment of structural seismic capacity performed by nonlinear static pushover analysis implemented on the lumped plasticity model of the structure. In order to allow the structure to withstand 0.30g PGA seismic actions, a retrofit using glass fiber‐reinforced polymer (GFRP) laminates was designed. The retrofit design was targeted to achieve a more ductile and energy dissipating global performance of the structure by increasing the ductility of columns and preventing brittle failure modes. Design assumptions and criteria along with nonlinear static pushover analysis to assess the overall capacity of the FRP‐retrofitted structure are presented and discussed. After the retrofit execution, a new series of PsD tests at both 0.20g and 0.30g PGA level were carried out. Theoretical predictions are compared with the main experimental outcomes to assess the effectiveness of the proposed retrofit technique and validate the adopted design procedures. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献