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.     

A Transfer Precision Study of Interior Horizontal Coordinates of Oblique Super High Rise Buildings

When staking out super high rise building construction, it is important to analyze the horizontal coordinate precision of the control point of the axis. For coordinate transfer of control points of oblique super high rise buildings with high accuracy and precision, methods combining the electronic tachometer with laser aligner were adopted. The measurement sections were transited by sections many times on the floors. The coordinates of control points of lower floors gradually were transferred to the top floor by relays. We then could use the electronic tachometer to measure the linear distance between the control points of each floor and the control point of the axis, calculate the coordinates of the axis control point, and analyze the precision of the coordinates. Thus, integrated methods of transferring horizontal coordinates of super high rise buildings setting out of axis repeatedly can be taken from the control points to the monitoring points section by section. The precision integrated methods improve the coordinates of the control point of the axis by adopting advanced measurement equipment. We recommend choosing an electronic tachometer with different precision and a laser aligner to analyze the control point error quickly and accurately, provide a complete and systematic method for optimizing the staking out scheme in construction, and guide the staking out work and deformation monitoring work of super high rise buildings or oblique super high rise building construction.     

Dynamic Response Analysis of High-rise Pile Cap-soil-structure under the Wave and Earthquake Action

Finite element software was used to simulate the internal force and deformation of high-rise pile cap-soil-structure under the wave and earthquake action. Meanwhile, wave force was calculated by using Morison equation, and the mechanical behavior of structure was simulated by inputing horizontal El-Centro wave. Then, the initial state and the state of the largest positive and negative acceleration were selected to study the structure according to the time history curve, and the displacement, bending moment, shear and axial force changes of pile foundation under wave and earthquake action were discussed, which was compared and analyzed with the structural response under the action of earthquakes solely. The result shows that the moment of front row of piles is biggest, and the force of pile bolck is the most dangerous; the axial force of the corner piles is the largest, and one of the center piles is the smallest under the action of wave and earthquake. When the wave forces and seismic forces are in the same direction, the displacement, moment, and shear force of pile bolck will be increased, on the contrary, the displacement, moment, and shear force of pile bolck will be decreased.     

Practical Method for Dynamical Analysis to the Interlayer Seismic Isolation Masonry Building with Frame Structure in the First Storey

Masonry buildings with R/C frame- shear wall in the bottom storey have been widely used in city construction, which include two kinds of lateral force resistant system. However, the seismic behavior of the building is poor. Based on the characteristics that the rigidity of the upper masonry structure is much bigger than the rigidity of laminated rubber bearings and frame structure. It can be referred to as system having a two degree of freedom. The dynamic behavior of this building is analyzed, the isolated vibration mode controls the response of system. The authors give apractical method for dynamical analysis to masonry building with frame structure in the first storey with laminated rubber bearings between the first and second storey , which submits efficient path to found applicable design means and to generalize interlayer seismic isolation structure.     

Earthquake of Steel Frames-the Seismic Performance of Composite Structural Systems of Concrete Core wall

The steel fame-concrete core wall combination of structural system is outside the framework with steel inner cylinder with concrete shear wall, steel frame-concrete inside the tube system. In this paper ,the finite element software ANSYS earthquake seismic response analysis and stability analysis, the 25-story steel frame-concrete core wall combination of structural system data results show that the structural system performance than the purity steel framework structure is superior.     

A Comparative Evaluation of Model Pushover and the Influence of Higher Modes

Three reinforced concrete plane frames with total heights of 6, 10, and 16 stories, respectively were taken as examples. Nonlinear dynamic responses of three frames under excitations of seven earthquake waves with varying earthquake intensities were selected as the datum mark of a comparison study. The changing rules of the responses analyzed by four kinds of ordinary Pushover Analysis and Modal Pushover Analysis were studied by reviewing the inter story drift ratio and rotation at beam and column ends. Results show that the error of inter story drift ratio analyzed by Modal Pushover Analysis essentially is invariable when the total frame height increases, while the error of ordinary Pushover Analysis is added corresponding to a larger fundamental period. This indicates that Modal Pushover Analysis can cover the influence of higher modes more reasonably. When nonlinear responses of frames were more severe, the inter story drift ratio errors of Modal Pushover Analysis and ordinary Pushover Analysis also increase correspondingly. The errors of rotation at upper story beam ends and the majority of column ends analyzed by Modal Pushover Analysis are smaller than those of ordinary Pushover Analysis.     

柱失效方程中荷载相关特性对承载力抗震设计可靠度的影响

以竖向荷载和水平地震作用组合下的钢筋混凝土柱和钢柱为对象,研究了失效方程中荷载相关特性对柱承载力抗震可靠性的影响。根据现行《混凝土结构设计规范》和《钢结构设计规范》分析了不同柱弯矩轴力相关曲线的特性。结合多个框架结构实例,对比了柱失效方程中荷载相关曲线与规范考虑情形的异同。实例分析表明:水平地震和竖向荷载组合作用下,小偏压RC柱和工字型钢柱的荷载相关曲线与规范考虑的情形较为符合,均近似为负相关的直线;水平地震和竖向荷载组合作用下,大偏压RC柱的荷载相关曲线则与规范考虑的情形有较大出入,存在明显的正相关段部分。在此基础上,考虑失效方程复杂特性,依据已有的荷载和抗力变量概率模型,采用Monte Carlo法分析了水平地震和竖向荷载组合作用下柱的可靠性。结果表明:钢柱和小偏压RC柱的承载力抗震可靠度随轴压力荷载效应比值的变化幅度较小,与规范模式计算结果较接近;大偏压RC柱的承载力抗震可靠度随轴压力荷载效应比值的变化会有较大幅度波动,与规范模式计算结果差异较大;当轴压力荷载效应比值为负时,大偏压RC柱的承载力抗震可靠度会低于规范计算值较多,现行柱可靠性设计方法会偏于不安全。     

Experimental Investigation of Steel Frames with Infill Prefabricated Reinforce-Concrete Shear Walls

In order to improve seismic performance of steel frame with prefabricated reinforce-concrete infill shear walls (SFCW), the ear bar device was used in the connection between the steel frame and the infill wall. Two one-bay, two story and one-third scaled models of SFCW were tested with low cyclic load. The working performance of ear bar connection, the cracks development in infill walls and deformation performance of SFCW were investigated. And the failure mode, hysteretic behavior,stiffness degradation,deformation and ductility and energy dissipation of composite structure were analyzed. The comparison study of steel frame with prefabricated, cast-in-place and silt reinforce-concrete infill shear walls was carried out. The results show that no failure occurs in the connection between the steel frame and the infill wall because ear plates below and up the beam-to-column connections are added in the specimens, and the connection device of ear plate presents good working performance. The properly designed SFCW has good ductility.     

Experimental Analysis of Seismic Performance of Strengthening Frame-supported Reinforced Concrete Masonry Short-leg Shear Wall Structure Damaged by Earthquake Using the Sub-structure Pseudo-dynamic Test

Based on the damage assessment and strengthening scheme of the full-scale model which is the three-floor frame-supported reinforced concrete masonry short-leg shear wall structure, the strengthened model is tested using the substructure pseudo-dynamic testing method. The applicability of the proposed strengthening technique for the building damaged by earthquake is discussed. Thus, the seismic performance of the strengthened model is proposed to seek the strengthening technique for the structure damaged by earthquake, and it provides important reference for the post-disaster reconstruction after Wenchuan earthquake.     

Study on Equivalent Frame Model for Large-span Prestressed Concrete Residential Structure System

In this paper, a study is carried out on large-span prestressed concrete structure system in residence analyzed by specially - shape column equivalent frame model. Applying fiber model column-beam element and shell element, a large amount of comparative analyses about large-span prestressd concrete structure under horizontal and vertical load is carried out. The parameter of the equivalent frame is confirmed based on comparison with the result of the man-sized structural experiment. It is proved that the equivalent frame model has high efficiency and precision especially for nonlinear analysis.     

An improved method for and error evaluation of modal pushover analysis

Based on evaluation of the basic principle and error of the modal pushover analysis method, an improved method is suggested by selecting rational values of stiffness reduction parameters of beams and columns in a reinforced concrete frame corresponding to the global target displacement ductility ratio. A 10 story and a 16 story reinforced concrete plane frame are designed as examples to investigate the influence of higher modes. Nonlinear seismic responses of the two frames under excitations of seven earthquake waves of varying earthquake intensities are selected to be the reference points for a comparison study. The changing rules of the results of modal pushover analysis and modified modal pushover analysis with respect to various natural fundamental periods and different earthquake intensities are studied. Research results show that the error of modal pushover analysis and modified modal pushover analysis will not increase with a larger fundamental period, which implies that modal pushover analysis can cover the effect of higher modes reasonably. When the degree of nonlinearity of the structure is more severe, the modified modal pushover analysis we suggest could decrease the error of normal modal pushover analysis to a certain extent.     

Experimental Investigation on the Aseismic Behavior of Seismic Damage Masonry Wall Retrofitted with Grouting and Steel Hoops

In order to accurately evaluate the aseismic behavior of the seismic damaged masonry pagodas destroyed by Wenchuan earthquake and strengthened after the earthquake, a test was conducted to acquire related parameters on seismic performance from the specimens made by masonry and retrofitted with grouting and steel hoops. Taking a seismic damaged ancient masonry pagoda in Sichuan as a case study, four kinds of primitive specimens are fabricated by simulating the conformation of the masonry pagoda. Then the primitive specimens are destroyed under cycle loads and the damaged specimens are repaired by grouting and steel hoops. Cycle controlling tests are conducted with the specimens and relevant data are acquired. Experimental results showed that grouting combined with steel hoops could improve the ductility and energy dissipation capacity of a seismic damage of brick masonry structure, but it do a little to improve the stiffness of a seismic damage structure. And the cracking load of the repaired masonry is much lower than the original undamaged structure.     

钢结构仿古建筑双梁柱中节点的受力机理

为研究钢结构仿古建筑双梁柱中节点的抗震性能,对4个全焊双梁柱中节点进行了水平低周反复加载试验。通过观测试件在侧向力作用下的受力过程和破坏形态,分析双梁柱中节点的受力机理。根据梁截面形式的不同,将其分为箱型截面梁与工字型截面梁2类,依据仿古建筑独特的构造特点,将各试件节点核心区划分为上、中、下3个区域。通过量测各区域内的应变大小,分析该类结构节点核心区在侧向力作用下的受理机理及破坏模式,并建立双梁柱节点的斜压杆受力模型。试验结果表明：仿古建筑双梁柱节点的破坏形式主要为沿下核心区对角线的剪切破坏,并通过理论计算分析提出一种考虑轴压比与梁截面形式的双梁柱中节点抗剪承载力修正公式。     

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.     

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.     

RC加气混凝土砌块组合墙加固框架抗震性能试验研究

RC加气混凝土砌块组合墙（简称组合墙）是由混凝土梁柱网格与加气混凝土砌块组合形成的一种轻型网格式抗震墙,可用于框架结构的抗震加固。笔者进行了1/2比例空框架试件、组合墙试件和组合墙加固框架试件的低周反复荷载试验,分析了各试件的主要破坏过程,对比了组合墙加固框架前后试件承载能力、刚度等抗震性能变化。试验结果及分析表明：组合墙加固框架后承载力、抗侧刚度有较大幅度提高,中大震及大震阶段其承载力、等效刚度约为空框架和组合墙单独受力之和的0.9倍,两者具有良好的协同工作性能;加固试件的破坏过程基本上遵循填充砌块混凝土框格外框架的破坏顺序,能够发挥组合墙多重抗震防线的特点,采用RC加气混凝土砌块组合墙加固框架是一种较为经济实用的加固方法。     

Seismic Behaviour of Multi Story Brick Building with Frame Shear Wall in the Two Botton Floors

A shear vibrational model applied assemblage of multiple particles is proposed for the seismic response analysis of masonry building with R/C frame wall in the two bottom floors.On the basis of analyses,some problems are discussed,these mainly are:dynamic properties,main factors that have influence on seismic behavior,earthquake resistant reliability of this building under strong earthquake and the rational ratios of lateral rigidity.[WT5HZ]     

Seismic Behavior of a Slope Protected by a Soil Nailing Retaining Wall during an Earthquake

The dynamic elastic plastic finite element method was used to study the seismic performance of a slope protected by a soil nailing retaining wall. On the basis of working in parallel and interaction between loess and a flexible retaining wall, a 3 D nonlinear finite element method (ADINA) also was established. Rational earthquake excitation and damping were discussed for geological engineering. Horizontal and vertical excitations were considered simultaneously in the analyses. A model capable of simulating the nonlinear static and dynamic elastic plastic behavior of soil was used to model the soil, and a bilinear elastic plastic model having hardening behavior was used to model the soil nailing. A friction element was employed to describe the soil structure interaction behavior. Our research focused on the seismic performance of the horizontal and vertical slope deformation, soil nailing axial force, and earth pressure subjected to horizontal and vertical excitations. The results show that the seismic performance of slope protected by soil nailing is good; soil nailing axial force increases after an earthquake; permanent slope displacement occurs during an earthquake; and the peak earth pressure distribution during an earthquake is similar to the earth pressure before the earthquake. These conclusions can provide references for seismic analyses and design in soil nailing engineering.     

RATIONAL DETERMINATION OF TNE BEAM AND COLUMN CROSS-SECTIONAL SIZES OF THE FRAME STRUCTURE IN A EARTHQUAKE ZONE

At the preliminary design stage of a building, it is neccssary to determine thebeam and column cross-sectional sizes of frame strtictures.According to some provisions of the"Building Aseismatic Design Code"(GBJ 11-89),main factors having influence on the beam andcolumn cross-sectional sizes are analyzed.and calculating formulas for the determination of the beam and column cross-sectional sizes which are satisfied the restrained condition of horizontal dis-placement of a building are derived in this paper.     

Suitability of Bi-linear Restoring Force Model in Earthquake Response Analysis

Based on the data of dynamic tests of small single-storey steel frames,the suitability of simplified hi-linear restoring force model in earthquake response analysis is discussed, and the Maximum displacement response MD, the sum of squares of the displacements in the whole vibrating history SSD, and the total dissipated energy EI are considered respectively as equivalent object.