RPC-NC组合梁界面受力性能研究

Interface Mechanical Behavior of RPC-NC Composite Beam

为适应高速铁路快速发展对桥梁使用性能的要求,设计12组共36个活性粉末混凝土(RPC)-普通混凝土(NC)双面剪切试件,进行剪切静载试验,研究RPC-NC组合梁界面的受力性能。研究表明:RPCNC剪切试件在自然粗糙状态下受剪破坏时的相对滑移量在1mm以下,说明RPC-NC组合梁的黏结界面破坏前的滑移量很小,具有很好的整体性;其抗剪承载力随NC强度的增加而增加,且随界面压应力的增加而大幅增加;试件的破坏形态在界面压力较小时为界面的突然断裂,且随界面压力的增大,试件破坏前的荷载—滑移量曲线的延性有所增加;RPC-NC组合界面在自然粗糙状态下的极限剪应力τ与混凝土抗拉强度ft及界面压力σn之间的关系可用Mohr-Coulomb准则描述,并经过对试验数据的回归得到τ=0.41f_t+2.51σ_n。

In order to meet the demands for bridge service performance owing to the rapid development of high-speed railway, 12 groups of 36 Reactive Powder Concrete （RPC）-Normal Concrete （NC） double-sided shear specimens were designed and shear static loading test was carried through to study the interface mechanical behavior of RPC-NC composite beam. The results showed that under natural rough condition, the relative slips of RPC-NC shear specimens at shear failure interface were below 1 mm. This meant that the slip at the bonding interface of RPC-NC composite beam was very small before failure and good entirety of interface was observed. The shear strength of RPC-NC interface increased as the NC strength grade and the compressive stress of interface increased. The failure mode of specimen was the sudden fracture of the interface when the pressure of interface was relatively low. The ductility of the load-slip curves of speci- mens before failure increased as the pressure of interface increased. Mohr-Coulomb criterion was used to describe the relationship between ultimate interface shear stress τ, NC tensile strength ft and interface pressure an under the condition of natural rough state of RPC-NC composite interface. The expression τ= 0.41ft ＋2. 51σn was obtained through the regression of test data.