高强钢焊接薄腹工形截面双向压弯构件的稳定性

应用ANSYS有限元,分析了Q460高强钢焊接薄腹工形截面双向压弯构件的稳定性能,提出了可供实际应用参考的设计公式。分析中考虑的主要参数有腹板高厚比,构件长细比,翼缘宽厚比及荷载偏心率。结果表明,对受压为主的构件,腹板局部屈曲对构件稳定承载力影响较大,而对受弯为主的构件,这一因素对构件稳定承载力影响较小。有限元分析结果与现行规范方法计算结果比较表明,目前规范方法尚不能较好地计算高强钢焊接薄腹工形截面双向压弯构件的稳定承载力,因而提出了修正直接强度法,该法精度较好且偏于安全。     

Axial Force Stiffness Interaction in Seismic Analysis of RC Double Column Bridges

Earthquake induced dynamic axial force in reinforced concrete (RC) bridge bent columns will not only change the yield strength of the columns but also change their stiffness, which is seldom considered by the common lumped plasticity line model. Based on the fiber element model results that taking into account the influence of dynamic axial force on strength and stiffness simultaneously, the axial force stiffness interaction effect on the seismic responses of RC double column bridges was analyzed. The results show that, axial force stiffness interaction has a large effect on the seismic responses of the double column bridge in the elastic range, and it does not alter the ultimate capacity of the columns. Since the stiffness of the columns under compression and tension dynamic axial forces offset each other, the global displacement of bridge bent with equal columns is relatively unaffected by the axial force stiffness interaction, however, the differences of the column member forces are manifest. For the short column controls the global stiffness, the axial force stiffness interaction has significant influences on both the global displacement and member force responses. The influences become larger as the irregularity of the bridge bent increases, so the interaction between axial force and member stiffness should be sufficiently considered in seismic analyses.     

Experimental Analysis on Axial Compressive Behavior of R- CFTStub Columns with Prestressed Binding Bars

In order to investigate the effect of prestressed binding bars on axial compressive behavior of rectangular concrete-filled tubular (CFT) short columns, five rectangular CFT short columns, three with prestressed binding bars, one with ordinary binding bars, the other with no binding bars, were constructed and tested under axial compressive loads. The binding bars were made up with high-strength bolts. As used for ordinary binding bars, the high-strength bolts were welded to the steel tube before the column was loaded to axial compressive force. As used for prestressed binding bars, the high-strength bolts were first tensed by screwed screw cap down to bring force to prestress the steel tube and its core concrete, then welded to the steel tube before the column was loaded to axial compressive force. Test results indicate that the bearing capacity and ductility of rectangular CFT short columns are increased by setting binding bars. Compared to ordinary binding bars, the prestressed binding bars can decrease the longitudinal displacements corresponding to ultimate strength, but have little effect on the ultimate strength and displacement capacity after ultimate strength of the columns. The longitudinal displacements corresponding to ultimate strength of the columns decrease with the decreasing of space between binding bars. With the same section width and amount of binding bars, the bearing capacity of the columns improves with the increase of section long-broad-ratio, while displacement capacity after ultimate strength decreases with the increase of section long-broad-ratio.     

Shear Performance of Steel Plate with Trilateral Constrained

The load carrying test for four steel plate shear walls specimens with various ratio of width thickness are carried out so as to test the failure mode and the shear strength of steel plate with trilateral constrained, and the lateral stiffness and the buckling mode are investigated in the test. The result indicates that the ratio of width thickness of steel plate exerts effects on the shear carrying capacity and failure mode; the buckling of steel plate does not have lateral stiffness. Based on the failure mode of steel plate, the computation model of lateral performance is presented by theoretical analysis. The restraining stiffness of double angle and the buckling restrained stiffness of steel plate are the important design conditions. Formulae to determine the elastic lateral stiffness and the angle type is proposed, which can be used in the preliminary design of steel plate with trilateral constrained.     

配置600 MPa级高强钢筋T形柱抗震性能试验研究

600 MPa级钢筋是一种新型高强度钢筋,为研究该钢筋应用于异形柱结构体系的可行性,对7根不同轴压比、体积配箍率和钢筋强度的混凝土T形柱试件进行低周往复荷载试验,分别对其承载力、位移、滞回曲线、骨架曲线、刚度退化和耗能性能进行研究,综合评估其抗震性能。研究结果表明：配置600 MPa级钢筋的混凝土T形柱具有良好的变形能力和承载能力,提高配箍率能有效提高试件的抗震性能,提高轴压比可以提高试件的承载力,但降低其变形能力。随着钢筋强度的提高,试件的承载力显著提高。     

Elastoplastic Bending Buckling of Q420 Eccentric Compression Members with Double-angle Combined Cross-section

The experiments were carried out to investigate the behavior and failure modes of Q420 double-angle combined cross-section members whose specification were L160×12, L160×14, L160×16. The results show that all the members fail with an elastoplastic bending buckling. Based on the improvement of the inverse calculation segment length method and some relevant procedures, the related curves of axial force and moment with different specifications, different slenderness ratios and residual stresses were calculated. The calculation method of in-plane stability and column curves were proposed. The nonlinear power function model is appropriate for such members' moment-rotation relations under equal bending moments.     

X形配筋增强高强钢筋异形柱边节点抗震性能试验研究

通过对核心区应用X形配筋增强的高强钢筋异形柱边节点和同等条件下未被增强的高强钢筋异形柱边节点进行拟静力试验研究,对比分析异形柱边节点的破坏特征、滞回曲线、承载能力、位移及延性、刚度退化、耗能能力等抗震性能指标。研究结果表明,配置HRB500高强钢筋异形柱边节点比配置600 MPa级的边节点承载能低,但滞回性能好,变形能力强,刚度退化推迟,耗能能力强;在核心区加入X形配筋,均可以改善高强钢筋异形柱边节点的破坏特征,使边节点抗剪能力、变形能力、耗能能力增强,刚度退化推迟,提高异形柱边节点抗震性能,配置HRB500高强钢筋的试件核心区应用X形配筋加强后抗震性能提高效果更好。     

Overall Stability Design of Restrained H Section Steel Columns under Axial Load in Fire

The effects of the restraint stiffness ratio, the axial load ratio and the column slenderness on the buckling temperature and failure temperature of a restrained H section steel column under axial load in fire were studied with a calibrated finite element method (FEM) model. And the calculation methods of buckling temperature and failure temperature were proposed. The effect of the restraint stiffness ratio on the buckling temperature and failure temperatures could be expressed with an exponent curve while polynomial functions was appropriate for the effects of the axial load ratio and the column slenderness. The results of the proposed method were in good agreement with those by FEM method and on the safe side.     

Theoretical Analysis and Experimental Test of Full-scale Bamboo Scrimber Flexural Components

The bending tests and theoretical analysis of five full-scale bamboo scrimber components were conducted and the flexural behavior of bamboo scrimber was researched in detail. Results show that the typical failure modes of bamboo scrimber flexural components are the bamboo fiber fracture at the bottom and interlaminar shear failure near the neutral axis. The sectional stiffness control the design for the bamboo scrimber flexural components, the ratio of PL/250 of the load corresponding to the deflection limit value of L/250 and ultimate load Pmax has good stability. The relationship model of bending tensile strength fm and elastic modulus E was established by regression, which shows that the sectional stiffness expressed by the elastic modulus could predict the bearing capacity well. The plane-section assumption is still valid. The bamboo calculation methods of scrimber flexural components were proposed considering the materials properties of bamboo scrimber based on wood structure design methods. The design value of bamboo bending strength, shear strength parallel to grain and the elastic modulus E were presented preliminarily.     

Experimental Analysis on the Mechanical Properties of Concrete Composite Slabs with Precast Prestressed Rectangular Rib Panels

For the convenience of industrialized production and site operation,specification design of PPCRP (precast prestressed concrete ribbed panels) is discussed. In order to obtain ultimate bearing capacity,bending rigidity and crack resistance,four PPCRP with two types of spans are studied,and the results show that PPCRP can satisfy the requirements of bearing capacity in construction phase and can serve as stay-in place formwork. To verify the mechanical property,shear behavior on contact interface of composite member and moment redistribution factor of continuous composite member,two single-span composite members and one two-span continuous composite member are studied. It is indicated that computational method for bearing capacity of composite member can be the same as cast-in-situ concrete slab. Besides,section strain analysis for composite member in two-loading is conducted,which suggests that thickness of bottom board can be used as calculated height with the consideration of two-loading.     

HDPF加固钢筋混凝土柱抗震性能试验研究

为了研究高延性聚酯纤维加固钢筋混凝土柱的抗震性能,共进行了7根柱的低周反复试验,其中,3根在未加固状态下进行试验,4根柱粘贴高延性聚酯纤维加固后进行试验,针对位移延性系数、等效粘滞阻尼系数、总耗能、承载力和纤维带的应变进行了研究与分析。研究结果表明：未加固柱的承载力、耗能能力和延性都比较低,采用高延性聚酯纤维加固后的试件裂缝发展缓慢,加固后柱的承载能力、耗能能力、延性均有不同程度地提高;在塑性铰区域内增加局部配筋,能够提高纤维布的约束效果。     

Experimental Analysis of Extension Length of Shape Steel in SRC-RC Transfer Column

Seismic performance of SRC-RC transfer column was analyzed based on experiment of 12 specimens of transfer columns and 1 RC specimen under low cyclic reversed loading, which mainly focused on the extension length of shape steel. Analysis and comparison on skeleton curves of specimens was carried out. Analysis was completed for ductility, bearing capacity, energy dissipation capacity and degeneration ratio of strength. Displacement ductility changes with the increase of extension length of shape steel, enhancing at first, then reducing, and reaching peak value when extension length is close to three fifths of column height. Extension length of shape steel has little effect on bearing capacity. Energy dissipation capacity of transfer columns has relationship with many factors. Three fifths of column height is rational for extension length of shape steel, and specimens have not only advanced performance of energy dissipation but also good stability of stiffness and strength in this condition. The bond performance between concrete and shape steel decreases with the increment of extension length of shape steel, and hence stability of strength decreases.     

Experimental Analysis of the Behavior of Steel Plate-masonry Composite Wall-beams

When steel plate-masonry composite structure used in the existing masonry structure with load bearing walls is removed for a large space, composite action should be considered between the beam and the supported masonry wall due to the arch effect formed in the supported wall. In order to investigate the working mechanism, failure mode, and load-carrying capacity, strain distribution in critical sections and mid-span defcection of this type of composite wall-beam, five steel plate-masonry wall-beams were tested under concentrated loads and analyzed, which considered variables of height-span-ratio of supported masonry wall, height-span-ratio of composite beam and thickness of steel plate. The results show that steel plate-masonry composite wall-beam starts failure from the masonry located at the line between loading point and supporting point; strain distribution of steel plate along section height meets the plane section assumption; the height-span-ratio of supported wall can directly influence the failure mode of masonry wall, buckling load corresponding to steel plate experiencing local buckling and ultimate load of tested specimens; the reasonable height of supported masonry wall is beneficial to the formation of composite action between supported masonry wall and composite beam, and the excessive high masonry wall will reduce the ultimate load of the tested specimen. Finally, the reasonable range for height-span-ratio of supported masonry wall was presented, and the proposed value representing the flexural stiffness of the steel plate-composite beam relative to the in-plane stiffness of the supported masonry wall was at least more than 79.     

高温下钢管约束型钢混凝土柱的受力性能

火灾下无防火保护的结构构件温度会迅速上升,从而造成钢材和混凝土的强度明显下降。为了研究火灾下钢管约束型钢混凝土柱的受力性能,考虑火灾下钢管约束型钢混凝土柱的不均匀温度分布及温度对材料力学性能的影响,提出了火灾下受轴心荷载作用的钢管约束型钢混凝土柱承载力的计算方法。利用有限元软件ABAQUS对提出的计算方法进行了验证,结果吻合较好。进而采用该计算方法对影响高温下承载力的参数进行了分析,研究表明：随着构件截面尺寸的增加以及混凝土强度和钢材强度的提高,构件的承载力逐渐增加,而钢管壁厚的改变对承载力并无太大影响。利用有限元软件ABAQUS分析了荷载比、构件尺寸、钢管壁厚等因素对构件耐火极限的影响,发现耐火极限随着荷载比和钢管壁厚的增加而减小,随着构件尺寸的增加而增大。     

Experimental Analysis on Beam-column Behavior of Steel-concrete Composite Pylon

Ten specimens with perforated ribs, which can be divided into two series, were made to observe the behavior of steel-concrete composite pylon under axial load and cyclic load respectively. The experiment reveals the ultimate capacity and failure mode of two types of specimens under the cyclic load with different actual axial load level. Furthermore, it can be concluded from the results that the failure mode can be divided into two types, that is compression failure and tension failure. And the behavior of those specimens under cyclic load is influenced significantly under high axial load or without axial load at all. In addition, perforated ribs will prevent the plates under compression from overall buckling effectively based on the observation that the wavelength of plate is limited between two neighboring perforated ribs. At last, comparison on the interaction behaviors of the axial load (N) versus moment (M) is made between the results of experiment and calculation according to the criteria.     

Axial Bearing Capacity Design Method of Cold-Formed Steel Quadruple-C Built-up Section Members

The finite element model involving geometric large deformation,materials and contact nonlinearity is established.Specimens of cold-formed steel quadruple-C built-up section members are simulated and the finite element models are proved to be valid.Then,numerical analysis on the behavior of specimens with different slenderness ratio and flange flakiness ratio are carried out,and then the axial bearing capacities of specimens are obtained.Based on effective width method and direct strength method (DSM) in related codes,two design methods of cold-formed steel quadruple-C built-up section members under axial compression are proposed:effective length method and correction factor method.It is shown that:the final failure characteristics of all specimens are local buckling and distortional buckling.In the case of not considering the reduction of effective length,the results calculated by each code are slightly lower than those of test and FEM when the slenderness ratio is less than 50,while the results are too conservative when the slenderness ratio is more than 50.     

Technical Economy Analysis on Selection of Structure About Soldier Pile

Based on silt geological condition, aimed at cantilever pile and pile-anchor, using method of beam on elastic foundation ,through multiple combinations of pile spacing, diameter, embedded-depth at different levels of excavation depth, the impaction is discussed on the greatest displacement, maximum bending moment, the largest shear forces of supporting structure, and in different excavation, bolt locations impact on maximum horizontal displacement, the greatest moment of medial and lateral bending moment, the biggest shear force of pile and the axial force of bolt. By deformation control standards of supporting structure, the law and technically feasible program is found. Then combined with construction method of pile and current quota, technical economy is performed to find the economic plan and give suggestion to the project.     

CFRP加固冷弯薄壁C型钢长构件的轴压承载力

为了研究CFRP加固冷弯薄壁C型钢长构件的承载能力,对腹板和翼缘均粘贴CFRP的试件进行了轴心受压加载试验。7根长度均为1 400 mm的试件,其中1根为未加固的控制试件,其余6根封闭缠绕外贴50 mm宽CFRP间距为50、100、150 mm 3种情况,层数为1层和2层。试验结果表明,在轴心荷载作用下的破坏模式为整体弯扭失稳,与控制试件相比,加固后试件的稳定极限承载力均有不同程度的提高;当CFRP间距与腹板高度的比值小于1时,加固效果较理想,且2层CFRP的加固效果好于1层。最后,采用有限元对模型进行数值模拟,对比试验数据和数值模拟结果,二者吻合较好。     

Finite Element Analysis of Hysteretic Behavior of PR Steel Frame-steel Plate Shear Wall

In order to investigate the seismic behavior of partially-restrained steel plate shear wall (Steel Plate Shear Wall, SPSW), the effects of partially-restrained connection on the hysteretic behavior, lateral bearing capacity, stiffness, energy dissipation of SPSW with strong and weak steel frame were simulated under low cyclic loading via equivalent strip model that had been verified by experiment. The results show that hysteretic behavior of SPSW has dual characters. The hysteretic curves of SPSW with strong surrounding steel frame become fat, and the hysteretic curves of SPSW with weak surrounding steel frame become narrow. With the increase of the bending capacity of PR connection, the hysteretic curves of SPSW become fat gradually, and the capacity of energy dissipation and lateral bearing increase. However, the effect on lateral stiffness of PR connection of SPSW with strong steel frame is higher than the one with weak steel frame.     

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。