反复荷载作用下锈蚀钢筋混凝土矩形柱力学性能研究

为了研究锈蚀钢筋混凝土矩形柱的抗震性能,本文采用了Abaqus软件,对钢筋混凝土矩形柱进行了数值模拟。本文分析了锈蚀率、轴压比、非加密区箍筋间距、纵筋直径等因素对其抗震性能的影响。研究结果表明,在反复荷载作用下,随着锈蚀率和非加密区箍筋间距的增加,RC矩形柱的水平向抗剪承载力明显下降,其延性也随之降低。增大纵筋直径可以有效提高RC矩形柱的抗剪承载力并增强其延性。然而,随着轴压比的增加,RC矩形柱的抗剪承载力显著提高,但其延性却明显降低。随非加密区箍筋间距增大,RC矩形柱的抗剪承载力和延性显著下降。

钢筋混凝土矩形截面柱绕丝加固的受力性能

采用200 t的压力试验机,对40根绕丝的钢筋混凝土矩形截面柱进行压力实验。针对绕丝的间距以及加载偏心距的不同进行了分组研究。结果表明,用绕丝加固的柱体可以提高承载能力和减少破坏时纵筋和混凝土的应变,并且提高的幅度随着绕丝间距的减小而增大。当绕丝间距为40 mm时,极限承载力提高5.5%,纵筋的应变提高了18%,混凝土的应变提高了38%,柱的延性能得到较大改善;绕丝加固法不适用于较大偏心受压柱。

工业回收钢纤维加固混凝土柱轴心受压试验研究

本文对采用工业回收钢纤维缠绕加固的钢筋混凝土矩形截面柱进行了轴心受压试验研究.本试验设计制作了6根矩形截面柱,其中2根分别为未加固柱和侧向粘贴钢板条未加固柱、4根均在侧向粘贴钢板条基础上缠绕钢纤维丝即分别为以10 mm间距的水平方式绕丝柱、以5 mm间距的水平方式绕丝柱、以20 mm间距的螺旋方式绕丝柱和以10 mm间距的螺旋方式绕丝柱.本文分析了钢筋混凝土矩形柱在轴心受压情况下,不同加固方式承载能力以及混凝土表面、纵筋和箍筋处应变的变化,比较了不同绕丝方式、不同绕丝间距对构件承载能力和延性性能的影响.结果表明,钢纤维绕丝加固可提高钢筋混凝土柱轴心受压承载力和延性性能,且绕丝间距越小,钢筋混凝土柱承载能力和延性提高的幅度越大.相同绕丝间距下,螺旋绕丝加固的钢筋混凝土柱承载能力及延性均优于水平绕丝加固.

Mechanical Behavior of Rectangular Steel-Reinforced ECC/Concrete Composite Column under Eccentric Compression

In order to improve the seismic performance, deformation ability and ultimate load-carrying capacity of columns with rectangular cross section, engineered cementitious composite （ECC） is introduced to partially substitute concrete in the edge zone of reinforced concrete columns and form reinforced ECC/concrete composite columns. Firstly, based on the assumption of plane remaining plane and the simplified constitutive models, the calculation method of the load-carrying capacity of reinforced ECC/concrete columns is proposed. The stress and strain distribu- tions and crack propagation of the composite columns in different states of eccentric compressive loading are ana- lyzed. Then, nonlinear finite element analysis is conducted to study the mechanical performance of reinforced ECC/concrete composite columns with rectangular cross section. It is found that the simulation results are in good agreement with the theoretical results, indicating that the proposed method for calculating the load-carrying capacity of concrete/ECC composite columns is valid. Finally, based on the proposed method, the effects of ECC thickness, com- pressive strength of concrete and longitudinal reinforcement ratio on the mechanical performance of reinforced ECC/ concrete composite columns are analyzed. Calculation results indicate that increasing the thickness of ECC layer or longitudinal reinforcement ratio can effectively increase the ultimate load-carrying capacity of the composite column with both small and large eccentricity, but increasing the strength of concrete can only increase the ultimate Ioad- carrying capacity of the composite column with small eccentricity.

Near Surface Mounted Application for the Strengthening of Rectangular Reinforced Concrete Slender Columns under Eccentric Load

The behavior of slender columns under the effect of eccentric loading has always taken the attention of researchers. When investigating the strengthening of reinforced concrete columns, mainly short and circular columns are the targeted elements. This is why the data about slender columns with rectangular sections is limited and infrequent specially when loaded eccentrically. This paper aims to increase the available experimental data in this specific area. The experimental program consisted of twenty seven specimens. The specimens were divided into three groups; one control group and two groups strengthened using two strengthening schemes. Scheme 1 implied the use of near surface mounted （NSM） longitudinal steel bars, while in scheme 2, NSM longitudinal steel bars partially wrapped with one ply of carbon fibers reinforced polymers （CFRP） sheets was used. The test specimen had an overall length of 2000 mm and a 100 x 200 mm rectangular cross section. In addition to the strengthening schemes, the test parameters included three ratios for the internal longitudinal steel bars ＂μ＂ 1%, 1.57% and 2.26%. The parameters were extended to cover three stirrups＇ volumetric ratio ＂ρv＂ 0.73%, 0.49% and 0.37%. The specimens were tested under the effect of eccentric loading with eccentricity-to-section height e/h equals 0.25. The research revealed that the strength gain in specimens strengthened with scheme 2 was higher than with scheme 1. Analytical modeling of the stress strain relation of the strengthened RC columns considering the effect of strengthening scheme, internal reinforcement ratio μ, and stirrups＇ volumetric ratio ＂ρv＂ was proposed. Verification was made using available experimental data. The proposed model showed a reasonable agreement with the experimental results.

津湾广场9号楼超限高层结构方案形成过程

津湾广场9号楼超限高层主楼平面尺寸为50.1m×50.1m,地下4层,地上70层,建筑面积约为15万m2,总建筑高度299.65m,为超限高层建筑。由于建筑功能需要,该超限高层建筑立面存在多处收进,结构方案的合理布置是满足建筑功能要求以及降低工程造价的关键。介绍了该超限高层结构方案的整个形成过程,最终的结构方案满足建筑功能的要求,且传力合理,具有较好的经济性,并通过了超限审查。