预应力RPC吊车梁正截面静载承载力试验研究

Experimental Study of the Bearing Capacity of Normal Section for Prestressed RPC Crane Beams

活性粉末混凝土(Reactive Powder Concrete,简称RPC)是一种新型超高性能混凝土。为了研究其构件的受弯性能,制作了二根吊车梁进行静载试验,通过分析其受力至破坏的整个过程,得到了吊车梁在各级荷载作用下最不利截面应变沿高度的分布图,建立了考虑受拉区拉应力贡献的正截面开裂弯矩和极限弯矩计算公式。研究结果表明,预应力活性粉末混凝土受弯构件,在开裂前可以按弹性方法计算,将受压区简化为三角形,受拉区简化为梯形。在计算截面抵抗矩塑性影响系数时,纵筋率越高,梁的开裂弯矩提高越大,其T形截面的抵抗矩塑性影响系数γm可近似取为2.1。考虑受拉区混凝土的贡献,受拉区应力图等效系数k可近似取为0.34。

Reactive powder concrete （RPC） is a new kind of uhra-high-performance concrete materials. In order to study the flexural performance of its components, two crane beams are test. By analyzing the beam＇s performance of the whole loading process till failure, strains along the height distribution for the most unfavorable section of the crane beam are obtained at all loading levels. The cracking moment and ultimate moment formulas are established with the tensile stress contribution considered. The research results show that before cracking the flexural member of prestressed reactive powder concrete can be calculated according to the elastic method, the compression zone is taken as a triangle the tensile stress diagram of concrete can be simplified as the trapezoidal. In the calculation of the plastic influence coefficient of the section resistance moment, the greater the longitudinal reinforcement ratio and longitudinal steel ratio, the higher the cracking moment of the beams. For the prestressed T section of RPC, the plastic influence coefficient γm can be taken as 2. 1 approximately; considering concrete tensile strength contribution, for the tension area of concrete the equivalent coefficient k can be taken as 0. 34 approximately.