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高温下足尺有粘结预应力混凝土梁板力学性能研究

发表时间:2014-01-31  浏览量:1378  下载量:546
全部作者: 郑文忠,闫凯,欧阳志为,王英
作者单位: 哈尔滨工业大学土木工程学院
摘 要: 高温下小尺寸预应力混凝土梁板力学性能试验结果不能反映足尺预应力混凝土梁板的抗火性能。基于纤维单元模型,采用应力迭代法求解热-力耦合本构方程,对高温下足尺有粘结预应力混凝土梁板的力学性能进行研究。结果表明:综合配筋指标、预应力度、有效预应力对有粘结预应力混凝土梁板高温下极限弯矩与常温下极限弯矩比值影响不大,但预应力筋保护层厚度对其影响显著。受火时间3 h、高宽比近似相同、且第一排钢筋的保护层厚度相同时,高度为700 mm的梁抗弯承载力衰减幅度最大约为80%,高度为4 500 mm 的梁抗弯承载力衰减幅度不到20%,大尺度梁的抗火性能优于小尺度梁。建立了考虑预应力筋保护层厚度影响的有粘结预应力混凝土板高温下极限弯矩与常温下极限弯矩比值的计算公式,以及综合考虑预应力筋、非预应力筋合力点到梁底距离和预应力筋梁侧保护层厚度的有粘结预应力混凝土梁高温下极限弯矩与常温下极限弯矩比值的计算公式,提出给定荷载状态和截面配筋的足尺有粘结预应力混凝土梁板耐火极限的计算方法。
关 键 词: 混凝土与钢筋混凝土结构;抗火性能;纤维单元模型;预应力混凝土;梁板
Title: Mechanical behaviour of the full-scale bonded prestressed concrete beams and slabs under high temperature
Author: ZHENG Wenzhong, YAN Kai, OUYANG Zhiwei, WANG Ying
Organization: School of Civil Engineering, Harbin Institute of Technology
Abstract: Fire resistance of the full-scale bonded prestressed concrete beams and slabs can not be reflected by experiment results of small-scale specimens exposed to fire. Based on fiber element model, stress iteration method is adopted to solve thermal-mechanical coupled constitutive equations, and the mechanical behaviors of the full-scale bonded prestressed concrete beams and slabs under high temperature are studied. The result shows that composite reinforcement index, prestress degree and effective prestress have little effect on the ratio of limit moment under high temperature and normal temperature for bonded prestressed concrete of the beams and slabs, while the concrete cover of prestressed reinforcement has significant effect on the ratio. When the ratios of height to width are similar, and the concrete covers of reinforcement in the first row are the same, the biggest descent rate of flexural bearing capacity of beams under 3 h fire duration, which the height are 700 mm, is almost 80% attenuation, compairing with 20% for beams which the height are 4 500 mm. Fire resistance of large scale beams is better than small scale beams. The calculation formula on the ratio of bonded prestressed concrete slabs is established introducing the effect of concrete cover of prestressed reinforcement. The calculation formula on the ratio of bonded prestressed concrete beams is also established considering the distances between the bottom of beams and the force points of prestressed reinforcement and reinforcement. The calculation method on fire resistance of the full-scale bonded prestressed concrete beams and slabs is put forward.
Key words: concrete and reinforced concrete structure; fire resistance; fiber element model; bonded prestressed concrete; beams and slabs
发表期数: 2014年1月第2期
引用格式: 郑文忠,闫凯,欧阳志为,等. 高温下足尺有粘结预应力混凝土梁板力学性能研究[J]. 中国科技论文在线精品论文,2014,7(2):125-135.
 
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