旧拱桥风撑改造设计

Reconstruction Design of Wind Bracing of Existing Arch Bridge

某旧混凝土系杆拱桥跨径布置为(13+36+13)m,2片拱肋间设3道横向风撑。调查发现该桥存在风撑、桥面板、横梁损坏及多处裂缝等病害,两侧风撑桥面净高(实测)低于设计净高是导致风撑损坏的主要原因。为提高该桥的通过能力及保证其安全稳定性,对该桥风撑进行改造设计,采用有限元法分析原结构风撑、单风撑、无风撑、短K风撑和长K风撑5种风撑结构稳定性,并进行强度验算。经对比分析,该桥采用单风撑结构的改造方案,即保留原有拱顶风撑,拆除两侧的风撑,限高4.5m。风撑改造实施结果表明,单风撑方案施工便捷,既保证了结构安全又提高了桥梁通过能力。

The span arrangement of an existing concrete tied arch bridge is（13 ＋ 36＋ 13）m, three wind bracings are installed between two arch ribs. It is found through investigation that damage and multiple cracks have occured in the wind bracings, bridge deck and lateral beams of the bridge. The measured net clearance of the deck at the wind bracings is lower than the design value, which is the main reason accounting for wind bracing damage. To improve the passing capacity and ensure the safe stability of the bridge, the reconstruction design was made for the wind bracings of the bridge. The finite element method was used to analyze the structural stability of five wind bracing structures, such as the original wind bracing of the structure, single wind bracing, no wind bracing, short K-shaped wind bracing and long K-shaped wind bracing, and to make strength verification. The reconstruction plan of using single wind bracing was determined through comparative analysis, namely keeping the original wind bracing in the arch crown, demolishing the wind bracings at the two ends and limiting the clearance to 4.5 m. The results of the reconstruction indicate that the plan of adopting single wind bracing eases the work of construction, guarantees the safety of the structure and improves the passing capacity of the bridge as well.