火灾下预应力混凝土T形截面梁破坏模式研究

发布时间：2018-09-07 18:51

【摘要】：为了给出火灾下预应力混凝土薄腹梁的破坏准则,针对火灾下预应力混凝土T形截面梁桥的破坏问题,研究火灾高温传导模式和热传导混合边界条件,设定预应力混凝土T形截面梁的火灾作用模式,分析其温度场分布状态,并给出预应力混凝土T形截面梁变形破坏的计算细节和判定条件。采用热力场耦合计算方法,研究不同火灾模式下预应力混凝土T形截面梁桥的破坏模式,跟踪不同火灾模式下预应力混凝土T形截面梁的梁肋变形和翼缘板变形路径。研究结果表明:仅预应力混凝土T形截面梁的梁肋受火时,梁肋的破坏时间和翼缘板的破坏时间相同,其耐火时间相对于其他受火模式较长;预应力混凝土T形截面梁下部单侧受火时,T形截面梁的截面产生显著畸变,受火侧翼缘板的破坏先于梁肋的破坏,破坏时间提前10min;预应力混凝土T形截面梁下部和顶部均受火时,两侧翼缘板的破坏均先于梁肋的破坏,破坏时间提前10min;预应力混凝土T形截面梁顶板受火或整体受火时,T形截面梁的破坏时间相对较早,为40~60min,顶板受火对预应力混凝土T形截面梁的耐火极限影响显著,该研究可为预应力混凝土薄腹梁的抗火性能研究和抗火设计提供理论依据。
[Abstract]:In order to give the failure criterion of prestressed concrete thin web beam under fire, aiming at the failure problem of prestressed concrete T-section beam bridge under fire, the fire high temperature conduction mode and heat conduction mixed boundary condition are studied. The fire mode of prestressed concrete T-section beam is set, the distribution of temperature field is analyzed, and the calculation details and judging conditions of deformation and failure of prestressed concrete T-section beam are given. The failure modes of prestressed concrete T-section beam bridges under different fire modes are studied by using thermal-field coupling calculation method. The beam rib deformation and flange plate deformation path of prestressed concrete T-section beams under different fire modes are followed. The results show that the failure time of the beam rib is the same as that of the flange slab when the beam rib of the prestressed concrete T-section beam is under fire, and the fire resistance time is longer than that of other fire modes. The section of T-section beam with prestressed concrete T-section is distorted obviously when the lower part of T-section beam is under fire, and the damage of flanking plate is prior to the destruction of beam rib. When the prestressing concrete T-section beam is under fire and the top of the beam is under fire, the failure of flange slabs on both sides of the beam is prior to that of the beam rib. The failure time of prestressed concrete T-section beam is 10 mins earlier than that of the whole T-section beam, and the failure time of T-section beam is 40 ~ 60 min. The fire of roof has a remarkable effect on the fire resistance limit of prestressed concrete T-section beam. The research can provide theoretical basis for the study of fire resistance and design of prestressed concrete thin web beam.
【作者单位】：长安大学公路学院;上海师范大学建筑工程学院;长安大学工程机械学院;
【基金】：国家自然科学基金项目(51308056,51108265) 国家留学基金委项目(201406565013) 交通运输部交通建设科技项目(2011 318 812 970) 中央高校基本科研业务费专项资金项目(310821172003)
【分类号】：TU378.2

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