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Measured temperature effects during the construction of a prestressed precast concrete bridge beam

机译:预应力混凝土预制梁施工过程中的温度效应

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Prestress losses in precast concrete beams include the short-term effects of elastic shortening and the long-term effects of concrete shrinkage, concrete creep and steel relaxation. Temperature effects are, however, excluded. The aim of this research was to monitor the behaviour of a prestressed precast concrete bridge beam, focussing on temperature effects and destressing. Successful monitoring assists in comparing the real performance of a structure to the expected design performance, and in managing the durability of the monitored structure. The effect of temperature variation on strains in prestressed beams was investigated by instrumenting a precast beam. Temperature and strains were monitored from the day of casting up to and including the cutting of the pretensioning strands. Daily temperature variations causing vertical non-linear temperature profiles resulted in internal strains of up to 28 % of the strains caused by destressing. It was therefore concluded that thermal effects before destressing resulting from elevated curing temperatures and daily temperature changes should be considered in the calculation of prestress losses. The monitoring techniques used were successful in determining the stresses and strains within the beam, which can be used to compare real prestress losses with the losses assumed in design.
机译:预制混凝土梁的预应力损失包括弹性缩短的短期影响以及混凝土收缩,混凝土蠕变和钢松弛的长期影响。但是,温度影响不包括在内。这项研究的目的是监视预应力预制混凝土桥梁梁的性能,重点是温度效应和去应力。成功的监视有助于将结构的实际性能与预期的设计性能进行比较,并有助于管理被监视结构的耐久性。通过测量预制梁,研究了温度变化对预应力梁中应变的影响。从浇铸之日直至预张紧线的切断(包括切断),一直监测温度和应变。每日温度变化会导致垂直非线性温度分布,导致内部应力高达28%的应力所引起的应力。因此得出的结论是,在计算预应力损失时,应考虑由升高的固化温度和每日温度变化引起的降压前的热效应。所使用的监视技术成功地确定了梁内的应力和应变,可用于将实际预应力损失与设计中假定的损失进行比较。

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