型钢-钢纤维混凝土组合结构的黏结破坏及传力机理研究

为了解决型钢混凝土组合结构的施工难题，利用离散的钢纤维代替传统钢筋笼，提出了型钢-钢纤维混凝土组合结构。以截面类型、钢纤维掺量、界面锚固长度和钢纤维混凝土保护层厚度为设计参数，进行了36个型钢-钢纤维混凝土试件的标准推出试验，研究了试件的受力性能，对破坏形态进行了统计归类，完成了损伤破坏全过程分析。试验结果表明：自由端与加载端的荷载-滑移关系并不同步，自由端先于加载端达到屈服；黏结劈裂裂缝首先出现在保护层厚度最小的钢纤维混凝土表面，然后由外向内发展，而黏结裂缝以型钢翼缘肢尖处为起点，沿45°斜向由内向外发展，直至达到钢纤维混凝土外表面；试件的破坏形态可分为黏结劈裂破坏、黏结锚固破坏、过渡破坏和型钢屈服破坏4种类型；型钢与钢纤维混凝土之间的黏结作用主要依靠化学胶结力、摩擦力和机械咬合力，推出试验的黏结滑移全过程可精细化地分为5个阶段和5个极限状态。

Bond failure and load transfer mechanism in steel and steel fiber reinforced concrete composite structures

In order to solve construction problems of steel reinforced concrete composite structures, the steel and steel fiber reinforced concrete composite structures are adapted by using steel fibers instead of traditional reinforcement cages. Considering the design parameters of section type, steel fiber ratio, interface embedded length and concrete cover thickness, the standard push-out tests of 36 specimens were carried out, the mechanical properties of specimens were studied, the failure modes were classified, and the full stage of damage was analyzed. The results show that the load slip relationship between the free end and loading end is not synchronous, and the load-slip curve at the free end yields prior to the loading end. The splitting cracks tend to appear at the area with the minimum concrete cover thickness and elongate from concrete surface to the steel, while the bond crack starts at the tip of the steel flange and elongate from the tips toward the concrete surface in the 45° direction until it reaches the outer surface of the steel fiber reinforced concrete. The failure of specimens can be divided into four modes, namely bond splitting failure, bond anchorage failure, transition failure and yeild failure of shape steel. The bonding interaction between steel and steel fiber concrete is mainly from chemical bond force, friction force and mechanical bite force. The whole process of bond slip performance can be divided into 5 stages and 5 limit states.