UPPC梁的开裂截面惯性矩及挠度计算研究  

MOMENT OF INERTIA OF CRACKED SECTIONS AND DEFLECTIONS FOR UPPC BEAMS

作　　者：杜进生[1] 区达光[2] 

机构地区：[1]北京交通大学桥梁工程系,北京100044 [2]香港大学土木广程系,中国香港

出　　处：《工程力学》2014年第2期170-176,共7页Engineering Mechanics

基　　金：香港研究资助局基金项目(RGC Project No.HKU 710111E)

摘　　要：为满足无粘结部分预应力混凝土（uppc）梁正常使用极限状态的设计要求，必须合理估算使用荷载下构件的挠度。由于预应力筋与其周围混凝士没有粘结，加之部分预应力混凝土梁的中性轴随外荷载而动，开裂截面形心轴及开裂截面惯性矩也跟着变，这给UPPC梁的挠度计算带来厂困难。该文建立了一个UPPC梁的开裂截面惯性矩计算方法，在此基础上，可以按Branson方法很容易地计算出截面有效惯性矩。该有效惯性矩与按《混凝土设计规范》（GB50010-2010）方法所得的有效惯性矩较接近，前者与后者之比在0．89-1．10。计算挠度与3个不刚研究者的试验对比表明所建屯方法足正确的并具有较广泛的适用性，可用于无粘结预应力筋为纤维复合材料的混凝土梁，而目前的混凝土结构设计规范方法则无法应用于此类构件。In the design ofunbonded partially prestressed concrete （UPPC） beams, it is necessary to estimate the deflection of the member under service loads so as to satisfy the requirements of a serviceability limit state. Because of the unbonding between the prestressing tendons with their surrounding concrete and the variation of the neutral axis with the applied moment, the centroid location of the cracked section varies and therefore the corresponding cracked moment of inertia varies too. It is not easy to determine the deflection of a UPPC beam. The moment of inertia of cracked sections is first determined for UPPC beams. Then, based on the Branson＇s method, the effective moment of inertias as well as deflections for UPPC members can be easily calculated. The computed effective moment of inertia is close to that from Chinese Code for Design of Concrete Structures （GB50010-2010）, and the ratio of the former to the latter is between 0.89-1.10. The computed deflections are compared with three researcher＇s test results, it is indicated that the developed method is correct and also applicable to UPPC beams with unbonded FRP tendons. While the current Chinese Code is not applicable to the deflections for UPPC beams with unbonded FRP tendons.

关 键 词：预应力混凝土 无粘结筋 梁 开裂截面惯性矩 挠度 

分 类 号：U448.35[建筑科学—桥梁与隧道工程]