悬臂浇筑箱梁0号块开裂原因分析及防裂措施

发布时间：2018-02-26 15:12

本文关键词： 连续刚构桥箱形梁号块支架现浇裂缝原因分析防裂措施　出处：《世界桥梁》2014年01期 　论文类型：期刊论文

【摘要】：某(65+120+65)m预应力混凝土箱梁连续刚构桥主梁分左、右2幅,0号、1号块采用支架一起现浇,左幅施工中拆模后发现0号块出现裂纹。为了解0号块开裂原因,采用间接热-结构耦合方法对0号块温度场和应力场进行有限元分析,并与混凝土随龄期变化的强度进行比较。分析结果表明,在单纯的温度场作用下和考虑墩身影响下混凝土箱梁关键部位应力均超出了混凝土抗拉强度,这是造成0号块混凝土开裂的主要原因。通过采用冷水拌制混凝土,在温度高、应力大的腹板与横隔板实体段内布置3层冷却水管,减小墩身和0号块浇筑龄期差,加密腹板水平向钢筋间距,在钢筋骨架外侧新增设成品钢筋防裂网片,延缓拆模时间、加强养护等防裂措施,有效地抑制了该桥右幅0号块混凝土开裂现象。
[Abstract]:The main girder of a 65 120 65 m prestressed concrete box girder continuous rigid frame bridge is divided into left and right two pieces. Block 0 and block 1 are cast-in-situ with the support together. In order to understand the cause of the cracking of block 0, the crack of block 0 is found after removing the formwork in the left frame construction. The temperature field and stress field of block 0 are analyzed by means of indirect thermal-structural coupling method, and the strength of concrete with age is compared with that of concrete. The results show that, Under the action of simple temperature field and considering the influence of piers, the stress of the key part of concrete box girder exceeds the tensile strength of concrete, which is the main reason for the cracking of concrete block 0. By using cold water to mix concrete, the temperature is high. Three layers of cooling water pipes are arranged in the solid section of the web and the transverse partition with high stress, which reduces the age difference between the pier body and the No. 0 block, increases the horizontal spacing of the web plate, adds the new anti-crack mesh of finished steel bar on the outside of the reinforcement skeleton, and delays the time of demoulding. Strengthening the crack prevention measures such as curing effectively restrains the cracking phenomenon of concrete on the right side of the bridge.
【作者单位】：中铁大桥局集团桥科院有限公司;桥梁结构安全与健康湖北省重点实验室;
【分类号】：U445.57

【参考文献】