两种不同环境下预应力混凝土梁疲劳破坏试验对比分析

发布时间：2018-03-29 01:38

本文选题：普通铁路　切入点：预应力混凝土梁　出处：《铁道标准设计》2015年09期

【摘要】：以我国目前普通铁路既有线上32 m跨度全预应力混凝土简支T梁为工程背景,通过12片1/6预应力混凝土模型梁非腐蚀环境和腐蚀环境下疲劳试验,对预应力混凝土梁疲劳破坏形态进行研究,对其破坏机理进行分析,结果表明非腐蚀环境下,恒、活载跨中弯矩在0.45Mu时为配筋合适的预应力混凝土梁疲劳破坏时的临界荷载点(Mu为跨中静载极限弯矩,临界点以疲劳寿命为200万次进行定义),超过该临界点后,需要适时加固;腐蚀环境下,梁底普通钢筋锈蚀后(预应力筋不锈蚀),疲劳损伤程度随锈蚀率增大而增大,锈蚀率越大疲劳寿命越短;锈蚀率7%为腐蚀疲劳破坏的临界点(临界点以疲劳寿命为200万次进行定义),超过腐蚀临界点以后,需要对预应力混凝土梁进行加固。两种不同环境下预应力混凝土梁疲劳破坏试验对比分析结果表明,预应力混凝土梁中非预应力筋虽然对静载承载力贡献不大,但是对疲劳抗裂作用明显,设计中应保证非预应力钢筋配置充足,包括充足的细密的箍筋、侧面纵向补充钢筋和梁底纵向抗裂钢筋、锚下螺旋钢筋等非预应力筋,以便分散裂缝宽度,提高疲劳破坏时的延性。
[Abstract]:Taking the 32 m span simply supported T beam of prestressed concrete on the existing railway line in China as the engineering background, the fatigue tests of 12 1 / 6 prestressed concrete model beams in non-corrosive environment and corrosion environment are carried out. The fatigue failure modes of prestressed concrete beams are studied and the failure mechanism is analyzed. The results show that the failure modes of prestressed concrete beams are constant in non-corrosive environment. 0.45Mu is the critical load point of prestressed concrete beam under fatigue failure, and the critical point is defined by fatigue life of 2 million times, when the critical point is defined by fatigue life of 2 million times, it needs to be strengthened at the right time. In the corrosion environment, the fatigue damage degree increases with the increase of corrosion rate, and the fatigue life is shorter with the increase of corrosion rate. The corrosion rate of 7% is the critical point of corrosion fatigue failure (the critical point is defined by fatigue life of 2 million times and exceeds the critical point of corrosion. It is necessary to reinforce prestressed concrete beams. The results of fatigue failure tests of prestressed concrete beams in two different environments show that the non-prestressed tendons of prestressed concrete beams have little contribution to the static load bearing capacity of prestressed concrete beams. However, the anti-crack effect on fatigue is obvious, and the design should ensure that the non-prestressed steel bar should be allocated adequately, including sufficient and dense stirrups, longitudinal reinforcement on the side and longitudinal crack resisting steel at the bottom of the beam, non-prestressed bars such as spiral reinforcement under the anchor, etc. In order to disperse the crack width and improve the ductility of fatigue failure.
【作者单位】：中铁第四勘察设计院集团有限公司;
【基金】：国家863高技术研究发展计划(2009AA11Z101) 国家自然科学基金(51278496)
【分类号】：U441.4

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