Thermal actions are considered in the design of bridges, as temperature variations can lead to restraint stresses and subsequent cracking. However, load descriptions are in some cases oversimplified or incompatible with modern applications, and background studies are limited. This paper therefore aims to develop a more detailed load description for the load case describing temperature differences between structural parts in bridges, focusing on portal frame bridges. The temperature in portal frame bridges is investigated by performing long-term thermal simulations using weather data from several locations in Sweden, and thereafter performing statistical analyses of the resulting temperature variations over time. The study gives suggestions of both characteristic and quasi-permanent values to be used in design based on the statistical analyses, and also notes a gradual change in temperature between structural parts, which could be considered in the design. The resulting quasi-permanent values are significantly lower than the values given in the Eurocode for temperature differences between structural parts, which, in turn, will lead to smaller and more realistic stress values in bridge design.

中文翻译：

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门式框架桥梁的空间温差

在桥梁设计中考虑了热作用，因为温度变化会导致约束应力和随后的开裂。然而，在某些情况下，负载描述过于简单或与现代应用不兼容，背景研究也很有限。因此，本文旨在为描述桥梁结构部件之间温差的载荷工况开发更详细的载荷描述，重点是门式框架桥梁。通过使用瑞典多个地点的天气数据进行长期热模拟来研究门式框架桥梁的温度，然后对由此产生的温度随时间的变化进行统计分析。该研究基于统计分析给出了设计中使用的特征值和准永久值的建议，并且还注意到结构部件之间的温度逐渐变化，这可以在设计中加以考虑。由此产生的准永久值明显低于欧洲规范中为结构部件之间的温差给出的值，这反过来又会导致桥梁设计中的应力值更小、更现实。