高强型钢超高性能混凝土短柱轴压性能试验及其有限元分析

EXPERIMENTAL STUDY AND FINITE ELEMENT ANALYSIS ON AXIAL COMPRESSION PERFORMANCE OF HIGH STRENGTH STEEL REINFORCED ULTRA-HIGH PERFORMANCE CONCRETE SHORT COLUMN

为研究高强型钢超高性能混凝土短柱的轴压性能,对试件进行了轴心受压试验,设计参数包括配钢率、箍筋间距和箍筋形式。观察了试件的轴压破坏过程,获得了破坏形态及轴向荷载-位移曲线,分析了承载能力、变形能力、刚度等轴压性能指标,以及超高性能混凝土、纵筋、箍筋和型钢的应变发展规律。在试验研究基础上,采用ABAQUS建立了高强型钢超高性能混凝土短柱轴压性能有限元分析模型,计算结果与试验结果吻合较好,进而进行了参数分析。结果表明:试件发生的是典型轴压破坏,中部表面出现“锯齿形”裂缝;轴向荷载-位移曲线会出现2次荷载峰值;箍筋间距减小时,试件的承载能力和变形能力均提高,但刚度退化速率没有显著变化;配钢率增大时,试件的承载能力提高,变形能力先增大后减小,刚度退化变缓;型钢强度增大时,试件的承载能力和变形能力均提高,提高速度先快后慢;超高性能混凝土抗压强度增大时,试件的承载能力提高,变形能力降低;超高性能混凝土受拉能够达到峰值应变;纵筋在极限点之前发生受压屈服;箍筋在极限点时应变不足屈服应变的1/3,但在破坏点前达到受拉屈服;型钢翼缘在极限点前后发生屈服,腹板屈服晚于翼缘。

In order to study the axial compressive performance of high strength steel reinforced ultra-high performance concrete(HSSRUHPC)short columns,axial compressive loading tests were carried out on specimens.The design parameters included steel ratio,stirrup spacing and stirrup form.The failure process of specimens under axial compression was observed,and the failure patterns and the axial load-displacement curves were obtained.The axial compression performance indexes such as bearing capacity,deformation capacity and stiffness,and the law of strain development of UHPC,of longitudinal reinforcement,of stirrup and of steel were analyzed.Based on experimental study,the finite element analysis models of axial compression performance for HSSRUHPC short columns were established by using Abaqus,and the calculation results agreed well with the test results.And then the parametric analysis was carried out.The results showed that the typical axial compression failure occurred for all specimens,and serrated cracks appeared at the surface of middle part.There are two peak values of load in the axial load-displacement curves.With the stirrup spacing decreasing,the bearing capacity and deformation capacity were both improved,but there was no obvious change in stiffness degradation rate.With the steel ratio increasing,the bearing capacity increased,the deformation capacity increased first and then decreased,and the stiffness degradation was slowed.With the strength of steel increasing,the bearing capacity and deformation capacity both increased,and the increase rate was fast first and then slow.With the compression strength of UHPC increasing,the bearing capacity was improved,but the deformation capacity got worse.The strain of UHPC could reach the tensile peak value and the longitudinal reinforcements yielded by compression before the ultimate point.The tensile strain of stirrups was smaller than one-third of the yield strain at the ultimate point but could reach the yield strain before the failure point.The flange of steel yielded by compression near the ultimate point,and the web yielded later than the flange.