高强型钢超高性能混凝土梁受弯性能试验研究及有限元分析

EXPERIMENTAL STUDY AND FINITE ELEMENT ANALYSIS ON FLEXURAL PERFORMANCE OF HIGH-STRENGTH STEEL REINFORCED ULTRA-HIGH PERFORMANCE CONCRETE BEAM

为研究高强型钢超高性能混凝土梁的受弯性能,以配钢率、型钢位置和钢纤维体积分数为变化参数,设计了6个试件,并对其进行了静力加载试验,获得了试件的破坏形态和荷载-跨中挠度曲线,分析了试件的承载能力和变形能力,以及型钢、纵向钢筋和超高性能混凝土的应变变化规律。基于试验研究,建立了高强型钢超高性能混凝土梁受弯性能的有限元分析模型,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:所有试件均发生的是适筋破坏,纵向受拉钢筋和型钢下翼缘率先屈服,然后受压区超高性能混凝土被压碎;在试件的破坏阶段,所承担的荷载会依次经历陡降、波动、缓慢上升和缓慢下降四个阶段;试件的变形能力系数超过5,呈现出较强的变形能力;试件开裂前,超高性能混凝土的应变符合平截面假定,但开裂后,只有受压区和受拉区在中和轴附近的一小部分超高性能混凝土应变呈线性分布;配钢率和型钢强度增大,试件的承载能力和变形能力均提高;超高性能混凝土抗压强度增大及型钢从截面居中位置下移,试件的承载能力提高,但变形能力下降;钢纤维体积分数增加,试件的抗裂能力和变形能力均提高,但承载能力变化不显著。

In order to study the flexural performance of high-strength steel reinforced ultra-high performance concrete(UHPC)beams,six specimens were designed and tested under static loads,with the variation parameters being the steel ratio,position of steel and volume fraction of steel fiber.The failure patterns and curves between load and mid-span deflection of specimens were obtained.The bearing capacity,deformation capacity and strain variation laws of steel,longitudinal reinforcements and UHPC were analyzed.Based on experimental study,the finite element analysis model of flexural performance of high-strength steel reinforced UHPC beams was established,and the calculated results were in consistence with experimental results.Then parametric analysis was carried out.The results showed that the appropriate reinforcement failure occurred for all specimens,and longitudinal tensile reinforcements and bottom flange of steel yielded first and then UHPC of compression zone was crushed.At the failure stage,the load experienced four stages,including sudden drop,fluctuation,slow rise and slow decline.The deformation capacity coefficients of specimens were larger than 5,showing strong deformation capacity.The strain of UHPC conformed to plane section assumption before cracking of specimen;but only the strain of UHPC at the compression zone and a small part of the tensile zone near the neutral axis distributed linearly after cracking.Higher steel ratio and steel strength lead to larger bearing capacity and deformation capacity of specimens.When the compression strength of UHPC increased and the position of steel moved down,the bearing capacity of specimens increased but the deformation capacity decreased.When the volume fraction of steel fiber increased,the crack resistance and deformation capacity increased,but the bearing capacity changed insignificantly.