缆索承重桥的缆索防雷技术研究

Research on Cable Lightning Protection Technology of Cable Supported Bridge

随着经济社会发展,缆索承重桥的应用越来越普遍,缆索是缆索承重桥受力核心构件,其特殊布置容易被雷击。然而根据现行防雷技术规范,桥梁设计和施工中通常只着重考虑索塔、主缆的防雷设计与施工,使斜拉索、吊索存在较大雷击风险,从而危及桥梁结构安全。为了避免斜拉索、吊索遭受雷击而损坏,确保缆索承重桥防雷安全,首先应用滚球法分析计算缆索承重桥遭受雷击的可能性,计算表明缆索易遭受天面和侧面的雷击;然后通过国家标准推荐的短时雷击和长时间雷击两种雷击试验波形对三个桥梁缆索样品进行了多次冲击试验,表明短时雷击对缆索使用寿命影响不显著,长时间雷击是影响缆索使用寿命的主要因素,甚至可能导致缆索断裂;进而提出缆索承重桥缆索的防雷措施。

With the economic and social development, the application of cable supported bridges is becoming more and more common. Cables are the core loaded members of cable supported bridges, due to their special location and features. Cables are vulnerable to lightning strokes.However, under existing lightning protection technical specification, and in the design and construction of bridges attention is usually only paid to the lightning protection design and construction of cable bent tower and main cable which can sustain the lightning strokes and sling in a high risk of lightning strike, thus endangering the safety of bridge structures. In order to protect stay cable and sling from lightning strike and ensure the lightning protection of cable supported bridges, calculations of the possibilities of lightning stroke on the cable supported bridges should be calculated by using the analysis of the rolling sphere method. Results show that cables are vulnerable to roof and side lightning strokes. Through multiple shock tests on three bridge cable samples relying on short-time and long-time lightning stroke test waveforms recommended by the national standard, it is shown that short-time lightning strokes have an indistinctive influence on the service life of cables while long-time lightning strokes are major factors influencing the service life of cables and even result in the rupture of cables. Therefore, lightning protection measures are taken and suggested for the cables used for cable supported bridges.