新型土坯墙体房屋抗震性能试验研究

提出了一种新型土坯墙房屋,对新型土坯墙房屋承重墙体的受力及抗震性能进行试验研究。设计三片新型土坯墙试件,研究土坯墙体在竖向荷载和反复水平荷载作用下的破坏过程、破坏形态、滞回曲线和骨架曲线特征以及墙体水平承载力和变形能力等,同时,研究新型构造措施对土坯墙抗震性能的作用。试验表明：新型土坯墙体的破坏模式与配筋混凝土小型空心砌块相似,土坯墙体具有良好的承载力和变形能力。新型构造措施对墙体整体抗震性能作用明显,其连接构造至关重要。与计算结果比较得出,在建筑抗震概念设计原则指导下,抗震设防7度区采用新型土坯墙建造二层房屋具有可行性。     

Analysis of Failure Mechanism of RC Structures with Specially Shaped Columns Affected by the Diaphragm

With the flexibility-based fiber model,the seismic behaviors of RC structures with specially shaped columns,designed according to the current code,are analyzed under unidirectional rare earthquakes using nonlinear dynamic analysis method.The beam strength is calculated with or without consideration of the diaphragm and its reinforcement.The results are compared and the conclusion has been drawn that the bending capacity of beams would be increased due to the effect of diaphragm and its reinforcement,and which would change the failure mechanism of RC frames under rare earthquake,especially in high intensity areas.Therefore the influence of the diaphragm should be considered during the seismic design of the type of structure.     

Seismic Performance Evaluation of a Steel Reinforced Concrete Frame-Concrete Tube Structure

In order to better understand the seismic performance of the hybrid structure, numerical analysis and shaking table model testing were conducted on a real tall building constructed in Beijing. The nonlinear analytic model of the structure was established with the aid of PERFORM-3D program, and the elastoplastic time-history analysis was performed. From displacement responses and energy dissipation of the entire structure, and deformations and plastic hinge forming condition of components, the response features under different earthquake levels were obtained. Based on the predetermined allowable limits of performance indices, the seismic performance of the structure was evaluated. In the mean time, the numerical analysis results were compared with test results. Both of test results and numerical analysis results indicate that the hybrid structure has good seismic performance.     

Interlayer Seismic Dynamic Analysis of Seismic Responses of Frame Structure

Earthquakes for the loss of life and property to people is immeasurable. Want to reduce such losses, on the one hand we hope that Government departments can forecast and notify you in a timely manner, on the other hand we need to develop anti-seismic structure of the building, reducing losses when the earthquake happened. Interlayer seismic isolation frame structure is the latest development of a seismic isolation structure.It compared with the ordinary seismic structural damping performance is better, had a large advantage.     

Inelastic Seismic Response of Reinforced Concrete Frame Structures Reinforced with HRB500 Steel Bars

To achieve sustainable development of construction industry, the application of HRB500 reinforcement with high strength and high ductility in RC structures is being promoted in civil and structural engineering in China. But few studies focus on seismic behaviors of RC structures reinforced with HRB500 bars. In this analysis, three RC frame structures on the Zone of Fortification Intensity 8 (0.3g) in China reinforced with HRB500, HRB400 and HRB335 bars respectively, are designed confirming to the latest draft of the revising Code for the Design of Concrete Structures. Then inelastic seismic response analyses of the three frames with multiple inputs of ground motions are conducted. The seismic response rules and seismic performances of the RC frame reinforced with HRB500 bars are compared with those frames reinforced with HRB400 and HRB335 bars. The analytical results indicate that under ground motions in rare earthquake level, the maximum displacements of the frame reinforced with HRB500 bars are roughly the same as those of the frames reinforced with HRB400 and HRB335 bars, while the rotation ductility demand of elements in the former structure is smaller than those of elements in the latter structures. It is also found that the frame reinforced with HRB500 bars develops a plastic energy dissipation mechanism that is dominated by beam hinges under major earthquake, and the maximum inter storey drift of the frame can satisfy the requirement in the Code for the RC Frame Structures.     

Calibration of Seismic Provisions for RC Frame in Different Earthquake-Intensity Regions in China

With examples of three 6-storey RC frames by using an elasto-plastic dynamic analysis program PL-AFJD of plane frame, developed by the second author of this paper, the frames designed for different earthquake-intensity regions (intensity category 7, 8, 9 respectively) are analyzed nonlinearly under four ground motions at the action of rare earthquake. Three frames strictly conform to the National Standard GBJ10-89 and the dimensions of columns are changed once along the height. The structure designed on intensity category 7 shows a relatively small response, which could be sustained by the structure. Though the hinge formation in columns can not be prevented, the inelastic deformation of columns is not serious, the structure at intensity category 9 exhibits a relative strong response, but the deformation of most columns is within the capacity and the trend to form a soft-storey does not appear. It is the structure at intensity category 8 that shows a severe response. Though the visible soft-storey can not be found, the deformation of some columns is beyond the capacity of inelastic hysteretic deformation under certain inputs, which indicate the possibility of local collapse.The elementary analysis results demonstrate the different effectiveness of seismic provisions for three different earthquake-intensity regions, which may be a reference to the amendment of National Design Standard.     

Influence of Pile-soil Dynamic Interaction for the Structure Elastio-plastic Deformation

It is necessary to analysis the structure elastoplastic deformation subjected to rare seismic action and the present methods are mostly based on the rigid foundation assumption, which give rise to the method considering the soilstructure dynamic interaction. Adopting the plan pile-soil-structure elastoplastic finite element models, the influence of soil- structure interaction for the structure elastoplastic deformation in the horizontal earthquake has been analyzed. Through analysing we found, considering interaction, the muhilayer-frame elastoplastic displacement was discounted, elastic displacement was minished in the weakness layer and the possibility of break was reduced. The elastoplastic deformation computed by the Code is conservative.     

刚性连体位置对非对称双塔连体结构动力可靠度的影响

考虑地震动的非平稳性,变化连体位置,对非对称双塔连体结构运用虚拟激励法进行非平稳随机激励下的动力可靠度研究。采用刚度退化的Bouc-Wen模型模拟塔楼各楼层的滞变特性,建立非线性化动力方程。运用混合精细积分法对每一时刻的响应进行求解,得到连体位置变化时非对称连体结构在非平稳随机激励下的时变方差。基于首次超越破坏准则与Markov假定,研究非平稳随机地震激励下连体结构的动力可靠度。运用上述理论,在8度罕遇地震作用下对某非对称双塔连体结构进行随机地震响应与动力可靠度分析。研究结果表明,地震作用下结构的层间位移响应呈现强烈的非平稳性,变化连体位置对连体结构的随机地震响应与动力可靠度将产生显著影响。     

基于FM信号的外辐射源雷达组网系统多传感器选择算法

提出一种基于调频广播（FM）信号的外辐射源雷达组网系统多传感器快速启发式算法,目的是使系统能够动态地协调各部FM信号接收机的使用,进而在资源有限的条件下达到更好的目标参数估计性能。该算法采用相干克拉美罗界（CRLB）作为代价函数,并通过贪婪快速启发式算法对优化问题进行了求解。仿真结果表明,所提算法不仅可以在系统资源有限的情况下提升目标的参数估计性能,而且可以大大减小计算量,具有很强的实用性。     

Building Damage in Mianyang City Caused by the May 12, 2008 Earthquake in Wenchuan, Sichuan Province, P. R. China

Summarizing building damage in all previous large earthquakes is an important approach to promote the development of structural seismic design. We conducted a statistical analysis of the earthquake damage to various buildings in Mianyang city, Sichuan province, P. R. China. This analysis was based on the emergency assessment and investigation of building damage in Mianyang city caused by the large earthquake that occurred on May 12, 2008 in Wenchuan. We also summarize the damage characteristics of different buildings and the lessons learned. We present the following findings and suggestions for structural seismic design:(1)Buildings in Mianyang designed according to current seismic code withstood the rare earthquake.(2)Different structural systems have obviously varied seismic behaviors. (3)Old buildings always have been the weak links in earthquakes, and should be evaluated and strengthened selectively after an earthquake.(4)Studies of anti cracking measures for masonry walls should be conducted. (5)Effective measures should be taken to reduce earthquake damage to non structural components, for example, infill walls in frames.(6)Seismic design methods and construction measures for stairs should be studied.     

A Preliminary Survey on Analysis Method of Building Structures Under Post-Earthquake Fire

Considering the impact of post-earthquake fire on building structures in structure design, an analysis method is proposed to analyze and simulate the response of building structures under post-earthquake fire. Based on the seismic response and thermal stress analysis, this method considers the structure seismic damage through a simplified seismic damage model, and the simulation of the response of building structures under post-earthquake fire was reached by linking the heat transfer analysis and thermal stress analysis to the results of seismic damage. A single-storey concrete frame and a multi-story concrete frame were analyzed with this method and compared with experimental results of the same concrete frame under fire without seismic damage. It is shown that the collapse mode may change for seismic damaged structures and the fire resistance decreases with the increasing of seismic damage degree.     

Verification and Improvement of the Effectiveness of Seismic Capacity Design Measures of Shear Wall

In order to investigate the effective seismic capacity design measures of shear wall and to realize expected failure modes under strong earthquake,the existing problems in current seismic capacity design measures are pointed out through theoretical analysis.The effectiveness of the measures of Chinese seismic design code is verified by fine finite element dynamic time-history analysis of examples.Improving measures are then put forward and are verified through example analysis.It is shown the bending ductile demand of bottom section of shear wall increases too much based on moment capacity design measures of Chinese seismic design code 2001 in the rigid foundation assumption under rare earthquake action,and its bearing capacity for vertical axis force loses;the shear capacity design measures of current seismic design code would lead to shear failure in the stores above the bottom ductility strengthening area.Some improved bending and shear seismic capacity design measures of shear wall are proposed and are verified to be effective.     

Seismic Analysis and Shaking Table Test of China Pavilion for EXPO 2010 Shanghai

China Pavilion for Expo 2010 Shanghai is designed with peculiar style and special structural system. The main structure is composed of four concrete tubes with steel-concrete composite floors. It is designed with a shape of inverted trapezoid in elevation. The fundamental vibration mode of this structure is a torsional mode due to the special shape with greater moment of inertia in upper floor, which exceeds the limit value stipulated in Chinese code. The seismic analysis of prototype is carried out by ANSYS program to evaluate its overall seismic performance and improve the structural design. At the same time, shaking table tests of a 1/27-scale structural model are conducted. It is faund that although the first mode is torsional, the torsional responses are not so large, which agrees well with the results of shaking table tests. Both the test results and calculation results demonstrate that the designed structural system satisfies the seismic damage patterns and meets the pre-defined performance objectives. Based on the test results, suggestions for improving design are also put forward.     

Seismic Behaviors of Frames in Frame Wall Structures under Rare Earthquakes on the Zone of Fortification Intensity 8 in China

To investigate the seismic behaviors of frames in frame wall structures (dual system), which may be different from those of frame structures, two frame wall structures were designed conforming to current Chinese design codes. One is a twenty four story building on the Zone of Fortification Intensity 8 (0.3g), and the other is a thirty story building on the Zone of Fortification Intensity 8 (0.2g). Then inelastic dynamic response analyses of the two structures were conducted with series of inputs of ground motions in a rare earthquake level. The seismic behaviors of the two structures were investigated preliminarily. It was found that the columns and beams of the frames in the frame wall structures did not experienced yielding under strong earthquake, while coupled beams in walls were the major energy dissipation elements with their post yielding plasticity. And the bases of some walls formed hinges as well. The reasons for the frames of dual system remained non yielding states were analyzed and discussed from the aspects of their favorable load carrying state and strengthening measures for them in dual systems in Chinese design codes. A preliminary proposal was made that it may be feasible to loosen moderately some seismic fortification measures concerning the frame in the dual system with a height exceeding 60m on the Zone of Fortification Intensity 8.     

Inelastic Seismic Response of Ordinary Reinforced Concrete Regular Frames

With an inelastic dynamic analysis program developed by the authors, seismic response analysis of regular RC frames designed to Chinese codes in different earthquake fortification zones are carried out. The results indicate that the displacement responses of structures are improved due to the more rigorous limitation on the inter-story drift under frequent earthquakes in the revised codes. The frames in seismic-intensity-9 zone designed to the former codes and the revised codes form plastic energy-dissipated mechanisms mostly With beam hinges, which can satisfy the requirement of seismic performance expectably. The frame in seismic-intensity-8 zone designed to the former code forms a plastic energy- dissipated mechanisms mostly with column hinges and shows a risk of occurrence of story-sway mechanism, while the frame in seismic-intensity-8 zone designed to the revised codes exhibits a relatively improved seismic performance but still with excessive column hinges, which suggests a need to further increase the column moment amplification measures for this kind of frames. The frame in seismic-intensity-7 zone shows a somewhat improved seismic performance than the frames in seismic-intensity-8 zone, but the protection to columns by the seismic measures is sill insufficient, which indicates that the column moment amplification measures for this kind of frames should be enhanced further.     

Seismic Concept Analysis of High-rise Diagrid Tube Structures

In order to study the seismic concept of high-rise diagrid tube-core tube structures,CFST diagrid tube-concrete core tube structures were designed based on typical project.The elastic-plastic time history analysis method is adopted and the components yield order is summarized based on their plastic developing processes.The influences of wall thickness,inclined column cross section and coupling beam height on the components yield order are studied and the distribution of seismic fortification lines between tubes are presented.The main factors exerting influence on structure lateral stiffness are analyzed and the key components of structure lateral stiffness and plastic energy dissipation are achieved.The seismic concept of this structure is discussed considering the three level earthquake fortification criterion and components yield characteristics at last.     

Statistical Analysis on High Strain and Low Cycle Fatigue Life of Rebars

High strain and low cycle fatigue(HSLCF)life of anti-seismic behaviors of rebars was investigaoted. Reliable theoretical basis was provided for data analysis on high strain and low cycle fatigue life of anti-seismic behaviors of rebars. The low cycle fatigue life of the HRB400 anti-seismic behaviors of rebars by quenching and self tempering (QST) process was tested. Because the low cycle fatigue life data was disperse, some kinds of mathematical statistics methods, such as Weibull double parameters probability function, normal distribution, lognormal distribution function and t-distribution function were used to statistically analyze the low cycle fatigue life data. The results indicate that in all of the probability functions, the low cycle fatigue life has the highest reliability by the t-distribution function method; the low cycle fatigue life has the lowest reliability by the normal distribution method; and the low cycle fatigue life has the highest safety by Weibull maximum likelihood method.     

TENTATIVE INVESTIGATION OF THE BEHAVIOR OF REINFORCED CONCRETE FRAME CORNER JOINTS UNDER LOW CYCLE LOADING

In this pager, four full-scale corner joint assemblies of reinforced concrete frame beam and column with different detail structure are tested under low cycle loading, The process of damage development and the characteristics of break of the assemblies in the course of alternately increasing positive and negative bending deformation are learned Strength, stiffness and ductility of assemblies and the various regulations of energy consumption are also studied. Compared with these properties, the anti-seismic behavior is tentatively commented. Besides, the test results of the strain distribution of beam and column longitudinal bars and stress state of joint stirrups are analyzed.     

Experimental Study on Seismic Behavior of Penetrated Interior Diaphragm on One Side Beam-to-Column Connection for Concrete-Filled Square Steel Tube

A total of three experimental specimens of penetrated interior diaphragm on one side had been tested under low-cyclic reversed loading to study the hysteric behavior,strength and stiffness degradation,ductility,energy dissipation capacity and the failure modes.The only difference of all specimens was the axial compression ratio.Experimental results show that the story drift ductility ratios are 2.11~2.32,and the energy dissipation ratios are 1.141~1.502 at the peak load.Additional anti-seismic design and research recommendations are presented.     

Improved Modal Capacity Spectrum Method for Estimating Seismic Performance of Structures

Performance-based seismic design involves how to confirm inelastic displacement demand of structures under earthquake in concise and reasonable way. Two shortages need to improve in analyzing the elastic-plastic seismic responses of structures if the traditional capacity methods are employed. The shortages are the uncertainty of equivalent high damp of elastic-plastic structures and the limitation of the higher order vibration mode effect being not taken into account. To solve these problems, the authors propose the concept and analyzing process of improved capacity spectrum method based on modal pushover analysis and the elastic seismic responses spectrum modified by strength reduction coefficient and ductile coefficient. The example of analyzing the performance of frame structure is shown which may be a simple and effective method used in engineering. This method has application potential in Performance-based seismic design.