页岩烧结保温砌块砌体基本力学性能试验研究

通过对页岩烧结保温砌块砌体轴心抗压、沿通缝抗剪、剪压复合抗剪性能试验研究,分析其破坏特征和破坏机理。试验结果表明:页岩烧结保温砌块砌体受压破坏时,在竖向灰缝附近形成主裂缝,接近极限荷载时砌体出现表皮剥落现象;沿通缝抗剪破坏模式主要为单剪破坏,脆性明显;剪压破坏有剪磨、剪压和斜压3种类型;实测轴心抗压强度平均值高于规范值,沿通缝抗剪强度、复合抗剪强度平均值低于计算值,并分别给出砌体轴心抗压强度平均值、抗剪、剪压复合受力抗剪强度平均值建议公式;剪压复合抗剪强度随着压应力的增大而增大;建立了页岩烧结保温砌块砌体受压应力应变关系表达式;给出该类砌块的弹性模量和泊松比的建议值。     

Experimental Research on the Seismic Behavior of the Interior Joint with High Shear - Compression Ratios in the Frame

The reversed cyclic loading tests of 5 nearly full-scale beam-column assembly specimens with high shear-compression ratio under different axial loads in reinforced concrete plane frames have been completed,which cover the shortage in the field of high shear-compression parameter among seismic joint experiments in the world.Based on relatively complete measuring and analyses of the law for the bond and slip of the beam bar through the joint,the stress of the level stirrup legs and hysteretic dissipated energy and the change of rigidity,the characteristic of shear transfer mechanisms and damage development and comprehensive seismic behavior of the assembly are proposed in this paper.It makes it possible to improve design codes and to establish relatively reasonable analytic modes and hysteretic modes in inelastic dynamic response analyses of the frame.     

Impact of Temperature in Air-conditioned Room on Blood Rheological Characteristics

Based on the reversed cyclic loading tests of 21 nearly full-size interior joints in completed reinforced concrete frames,the law of bond deterioration of beam bars crossing the joint is tested and analyzed,which is influenced by the axial load ratio,shear-compression ratio,reinforced bar strength,concrete strength and the relative length of beam bars crossing the joint. By the nonlinear fitting method, the formula of the bond stress r between steel crossing interior joints and concrete under different loading step is obtained. According to the loading approach, the propositional formula of the relative length of beam bars crossing the joint hc/d is presented, which is influenced by axial load ratio, shear-compression ratio ,reinforced bar strength and concrete strength.     

The Seismic Shear Capacity of I-Shaped and T-Shaped Reinforced Concrete Structural Walls

There are numerous shear walls with flanges in the high-rise buildings in P.R.China.The shear strength formula for shear walls in Chinese design codes lacks experimental data,while test results in other nations lack aseismatic shear strength test results for shear walls with flanges under axial force.In this paper,we report low-cyclic reverse load test results of shear wall models with large dimensions,one shear wall having an I-shaped cross-section and two with a T-shaped cross-section.We discuss why the aseismatic shear walls of high-rise buildings with large height-to-length ratios have small shear span ratios.We assess the reliability of the shear strength formulary in the Chinese codes for design of shear wall using the international shear wall test results.     

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.     

EXPERIMNTAL RESEARCH ON THE CRACK RESISTANCE AND BEARING CAPACITY OF PRESTRESSED BRICK MASONRY WALLS UNDER CYCLIC LOADING

By comparing the tests of prestressed and nonprestressed brick masonry walls with peripheral beams and Constructional columns, under cyclic lateral loading,the apperaence and development of Cracks,failure mechanism,hysteretic behavior,strength,stiffness,ductility and ener-gy dissipation of the brick rnasonry walls arc studied.Only the crack resistance and bearing capacity of walls are discussed in this paper.It is shown that prestressing on brick masonry wall can obviotisly improve its seismic behavior.Morcover,calculating methods for the crack resistance and the ultimate bearing capacity are presented,and the caculating results are identical with the tests.     

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。     

A Study on the Response of Brick Masonry Structure under Dynamic and Static Shear-Compression Loading and Suggested Shearing Equation

Based on the studies and experiments of the responses of brick model under dynamic and static shear-compression loading, this paper brought forward an equation as a transition one for standard of masonry structure design in revision and the standard of aseismic building design. With its simple form, definite concept and similar calculation results in comparison with those obtained by equations from two standards, this equation has realized the correlation of the old and new ones. Besides it is rather save, so it has given a new advice for the revision of the standards.     

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 Study on Shear Strength of High Strength Concrete Columns

On basis of the experiment on sixteen high strength concrete columns, their shear behaviors are analysed. The effects of shear-span ratio and axial compression ratio on failure behavior, cracking shear and shear strength are analysed. The authors have discussed the suitability of the design equations for shear strength in the code. This experimental study on shear strength of high strength concrete frame columns is the first one in this field at home and the results can be served as reference for the code of high strength concrete design.     

Experimental Research on Seismic Shear Capacity of I-Shape Ductile Reinforced Concrete Structural Walls

The shear design formula for seismic shearwalls in the Chinese standard (Code for Design of Concrete Structures) have not been verified by tests yet, In order to compensate for it, the authors undertake the task of testing on the shear behavior of seismic shearwalls organized by the Code association. After discussing on the particular conditions controlling tests and philosophy in specimen designing, the results of the first group of tests on the seismic shear behavior of shearwalls, which are I-shaped and with relatively large scale and axial force ratio of 0.2 and tested under reversed cyclic horizontal forces, are introduced. The results are analyzed and discussed.     

Full-Scale Test and Analysis of Mechanical Behavior of Concrete Filled Steel Tubular Column Node in Space Truss Structure

To investigate mechanical behavior and seismic behavior of concrete filled steel tubular column node (CFSTCN) in space truss structure, both full-scale test and Finite Element Method (FEM) were employed. The test load was 1.6 times of design load and by incremental step loading. Meanwhile, stress and deformation in CFSTCN were observed to monitor bearing capacity of the node. The results show that steel tubular works in elastic state and a small part of concrete beyond of compressive stress limits; steel tube and concrete adhesive well. The hysteretic energy dissipation capacity and failure mode under cyclic loading were revealed by nonlinear FEM. weakest position and ultimate bearing capacity of the node were obtained from FEM results. The method of combining full-scale test and FEM can well reveal the mechanical behavior and the seismic behavior of the node.     

Experimental Analysis of Time-dependent Shear Behavior on Stud Connectors

With regard to the long span continuous composite beams, the early composite shear stud strength at the joint surface between the steel girder and concrete slab at different concrete ages should be considered while the concrete slabs are casted by phases in construction stage. In this study, the push-out test of stud shear connectors were conduced at different concrete ages. Meanwhile, the change law of the ultimate shear strength, ultimate slip deformation, design shear strength, and shear stiffness of the stud shear connectors with concrete ages were analyzed, and the corresponding time-dependent calculation equations were presented. The results include that the main failure modes of stud shear connectors are the concrete slab splitting failure before 3-days concrete age. The load-slip laws of stud shear connectors at different concrete ages are basically the same, however, the shear strength and stiffness all increase with the concrete ages prolonging, and the increase degree is faster at early ages, but slower at later ages, which indicates that the early composite shear stud strength at the joint surface of composite beams should not be neglected.     

Calculation Method of Shear Behavior of Hybrid Fiber Reinforced High Performance Concrete Deep Beams

The static tests on hybrid fiber (steel fiber and polypropylene fiber) reinforced high performance concrete deep beams according to the orthogonal experimental design were conducted. The shear capacity and calculation method of deep beams were discussed as well. The contributory factors such as the characteristic parameters of steel fiber (types, volume fraction, aspect ratio), the volume fraction of polypropylene fiber, the ratio of web horizontal reinforcement and the ratio of web vertical reinforcement were analyzed. Results show that the shear failure mode of deep beams is changed with adding a reasonable volume of hybrid fibers, and hybrid fiber can greatly increase the diagonal cracking strength and shear strength of HPC deep beams. The diagonal cracking strength is increased by 45.2% averagely while the shear strength is increased by 25.6% averagely. A satisfied result is obtained when the plasticity theory is used to analyze shear behavior of hybrid fiber reinforced HPC deep beams. The contribution of web horizontal reinforcement and web vertical reinforcement to shear strength of deep beams is not obvious but the former plays a major role. After analyzing the strengthening mechanism of hybrid fiber, a formula to calculate the shear capacity of hybrid fiber reinforced HPC deep beams is presented based on spatial strut-and-tie mode and splitting failure.     

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。     

Design Method of Reinforced Concrete Sandwich Beam column Joints

The experimental results of reinforced concrete sandwich beam column joints were studied intensively and finite element method simulation of such joints were performed for the sake of design method.Basic design criterion and computation contents were provided according to failure mode of specimens and other experimental results.And the limits of parameters were proposed based on the analysis of seismic behavior influence factors and comparison of traditional joints and sandwich joints.Hence, formulas of load resistant capacity were acquired by the results of load resistant capacity of specimens and nonlinear finite element method simulation.It is found that three measures should be taken for sandwich joints in order to reach demanded ductility and load resistant capability.Firstly, several parameters should be limited, including shear compression ratio, axial load ratio, ratio of beam concrete strength to column concrete strength, and minimal amount of transverse reinforcement of joint.Secondly, shear load resistant capacity and axial compressive load resistant capacity should be computed to ensure load resistant capability of joint, and essential strengthen measures could be applied if necessary.Thirdly, appropriate construction details should be taken to avoid reducing of beam bar anchorage capacity.     

Seismic Load Tests on Reinforced Concrete Beam-Column Sandwich Joints with High Shear Stress

Seven reinforced concrete Beam-Column sandwich joint specimens were tested under cyclic load. The performances of these specimens consisting of loads resistance, deflection, ductility, displacement, energy dissipation could satisfy the requirement of structures for seismic design. The phenomena that concrete in joint region was crushed by axial load or eccentric load were never observed,and final failure for a multitude of specimens occurred by shear force. Though a few of performances such as beam bar anchorage capacity were not as well as those of traditional joints ,it is feasible for sandwich joints used while establishing structures.     

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.     

Simulation and analysis of mechanics of coal and gas delay outburst

The buried box girders in the mountain city sewage pipeline system would be turned into simple-supported girders because of the removal of the foundation caused by landslide.This change of supporting would result in the failure risk of pipeline structure.The static properties of the buried box girders with small depth-to-span ratio in simple-supported condition are experimentally analyzed.The failure pattern,shear behavior and shear lag effect of the buried box girders in simple-supported condition are studied.The shortages in the present design codes for the calculation of shear capacities of the box girders are also discussed.It is shown that under the vertical uniformly distributed load,the crack distribution of the box girders is uniform,and no major critical diagonal crack is formed,and the box girders lose the bearing capacity in the form of concrete diagonal rod crushing.As the main shear-bearing components,the stirrups devote much to shear capacity of the box girder after concrete cracking.The strains of the longitudinal rebars are affected by those factors such as the redistribution of internal force and cracks,so only few areas of the box girders show the shear lag effect.The change of supporting form leads to the premature cracking of concrete and affects the serviceability of the sewage pipeline.     

Transverse Seismic Design and Analysis of an H Type Bridge Tower Cable Stayed Bridge

According to our current bridge seismic design codes, the bridge tower is explicitly required to remain almost elastic even under the excitation of occasionally happened earthquake. To achieve this seismic performance objective, usually the steel ratios of tower base and strut are required to satisfy the static loading demand and increase by a large margin as well in most engineering practices which leads to engineering inefficiency as well as a rising seismic demand for the substructure. Therefore, the structural design parameters including the location, the stiffness and the constrain condition of the strut with respect to the tower column of H shape tower were studied to explore their effect on the transverse seismic responses of cable-stayed bridge tower, Moreover, the effect of yield intensity of the strut on the seismic responses of the tower column is also studied. The results show that the location and the stiffness of the strut have a slight effect on the seismic responses while the transverse seismic demands of the bridge tower decrease drastically when the constrain condition between the cross beam and the tower column changes.