有黏结与无黏结混合配置预应力筋混凝土梁短期刚度研究

Research on short-term stiffness of hybrid prestressed concrete beams with both bonded and unbonded tendons

针对有黏结与无黏结混合配置预应力筋混凝土梁的短期刚度问题,采用双直线法推导了混合配置预应力筋混凝土梁短期刚度的计算式。根据ABAQUS有限元软件建立的71根混合配置预应力筋混凝土梁的计算结果,对计算式中刚度计算终点的折减系数β_（0.5）进行多元回归分析,并根据β_（0.5）计算方法的不同,给出了两种计算混合配置预应力筋混凝土梁短期刚度的公式。利用已有文献中的42根无黏结预应力筋混凝土梁和31根有黏结预应力筋混凝土梁的试验数据,对提出的刚度公式进行了验证。试验结果表明：基于有黏结与无黏结混合配置预应力筋混凝土梁的短期刚度计算式,可推广应用于无黏结预应力混凝土梁和有黏结预应力混凝土梁短期刚度的计算。此外,根据收集整理的试验数据对中国GB 50010—2010、美国ACI 318-11和欧洲规范EN 1992-1-1：2004中预应力混凝土受弯构件刚度公式的计算精度进行了分析。

This paper presents an in-depth study on the short-term stiffness of hybrid prestressed concrete beams with bonded tendons and unbonded tendons. Calculation formulae of short-term stiffness were derived based on the double line theory. Multiple regression analysis is conducted for the reduction coefficientβ0.5 used for the termination point of the stiffness calculation, based on the finite element results of 71 beams. Two formulae for the short-term stiffness of the hybrid prestressed concrete beams were proposed based on two different ways of calculatingβ0.5·The test data of 42 unbonded prestressed concrete beams and 31 bonded prestressed concrete beams collected from existing literatures verified the proposed stiffness formula. It＇ s suggested that the proposed formulae for short-term stiffness can also be applicable to bonded prestressed concrete beams and unbonded prestressed concrete beams. In addition, this paper presents an assessment of the accuracy of design formulae provided by a number of design standards, including GB 50010--2010, ACI 318-11, EN 1992-1-1： 2004, for the short-term stiffness of prestressed concrete flexural members.