预制混凝土T梁早期裂缝原因分析

Investigation on crack effects of pre-stressed concrete T-beam at early stage based on finite element analysis

以某公路大桥施工过程中一榀跨径40 m的预应力混凝土T梁开裂的工程实际为例,采用有限元方法探讨了结构的损伤原因.采用有限元软件建立了该预应力T梁的有限元模型,分析计算了结构浇注后张拉前这段时间的受力情况.模拟了结构的时变温度效应及其对结构承载能力的影响.通过系统的参数分析研究了结构产生裂缝的原因、机理及裂缝的特征.研究表明浇筑温差及混凝土自身水化热引起的温度应力是导致结构出现裂缝的主要原因.研究结论对预应力混凝土T梁的裂缝防治提出了具有实际意义的方法,可以适用于其它类似结构的开裂分析.

A pre-stressed concrete T-beam with 40 m span of a highway bridge which cracked during construction stage was taken as the example to investigate the structural performance during the period of the pouring and stretching. The finite element method was applied to explore the reason for the crack expansion. The finite element model of the T beam was established with the aiding of the commercial package to investigate the structural stress distribution. The variations of structural performance induced by the time-varying temperature change were computed. The parametric study was carried out to examine the reasons for the crack expansion and the properties of the crack distribution. The results indicate that the temperature change in the pouring process and the heat of the hydration may induce substantial thermal stresses, which is the major factor to induce the structural cracks. Some measures which are proposed to prevent the structural cracks of the prestressed concrete T-beam during construction stage in this study can be applied in the crack analysis of similar structures.