大风区大跨连续刚构三角挂篮抗风加固分析及研究

Wind Resistance and Reinforcement Analysis of Triangle Hanging Basket Used in Large-span Continuous Rigid Frame Bridge in Windy Area

随着我国桥梁行业的发展,大跨度连续刚构桥的工程应用案例不断涌现。三角挂篮作为连续刚构桥悬臂施工中最常用的临时钢结构,在沿海台风作用下可能会发生较大的变形甚至导致整体破坏。本文针对平潭海峡公铁两用跨海大桥施工用三角挂篮,采用大型商用有限元设计软件MIDAS/CIVIL对其在台风荷载作用下的结构安全性进行了分析,量化三角挂篮在14级和16级台风荷载作用下的强度、刚度以及稳定性。在此基础上,对该三角挂篮进行加固,并对加固后的三角挂篮进行建模分析。研究表明,未加固的三角挂篮在14级和16级风荷载作用下发生整体变形,峰值位移分别达到5.1 m和7.7 m,远超过规范限值的要求。采用槽钢作为横向加固杆件,保证挂篮底部横梁形成几何不变体系,可以显著提高三角挂篮在风荷载作用下的工作性能,峰值位移和峰值应力分别为6.86 mm和46.4 MPa,均满足规范限值的要求。本文有限元分析结果可为实际工程施工提供理论依据。

With the development of domestic bridge engineering, numerous applications of large-span continuous rigid frame bridge have been witnessed. As mostly used steel structures in the construction of continuous rigid frame bridge, triangle hanging basket might occur large deflections or even lose their loading capacity under typhoon load. This paper presented the design and wind resistance analysis of triangle hanging basket used for highway and railway combined bridge over the Pingtan Strait. The background information and cross-sectional analysis of the triangle hanging basket was first introduced, and an FEM was then proposed by means of MIDAS/CIVIL to investigate their structural responses under typical typhoon with 14 and 16 magnitudes. Based on the FEA, the triangle hanging basket was strengthened and analyzed again. Results indicated that the original triangle hanging basket presented a maximum deflection of 5.1 m and 7.7 m, which was beyond the upper limit in accordance with current code requirements, the strengthened triangle hanging basket by means of channel steel showed excellent performance, with the maximum deflection and maximum stress of 6.86 mm and 46.4 MPa. Based on the finite element analysis results, suggestions were provided for similar projects.