高温下1770级φ~P5钢丝蠕变及应力松弛性能试验研究  

An experimental study on the creep and stress relaxation properties of 1770-φ~P5 prestressing steel wires at high temperatures

作　　者：张昊宇[1] 郑文忠[1] 

机构地区：[1]哈尔滨工业大学,黑龙江哈尔滨150090

出　　处：《土木工程学报》2006年第8期7-13,共7页China Civil Engineering Journal

基　　金：黑龙江省杰出青年科学基金(2001-8)

摘　　要：鉴于高温下预应力钢丝蠕变、应力松弛及温度膨胀性能是影响预应力结构抗火性能的重要因素,以1770级低松弛预应力钢丝为对象开展了研究工作。完成了25个钢丝试件的高温蠕变试验,得到钢丝高温蠕变应变与时间的关系曲线,建立起钢丝高温蠕变应变计算公式,揭示出蠕变应变随温度升高、应力水平增长及蠕变时间延长而增大的规律;提出考虑高温蠕变影响的钢丝持久极限强度计算公式,揭示了高温下钢丝持久强度与高温下极限强度的差值随温度升高而增大的规律。完成了26个钢丝试件的高温下应力松弛试验,得到高温下钢丝应力松弛与时间的关系曲线,建立高温下钢丝应力松弛的计算公式,揭示了钢丝初应力越大,所受温度越高,松弛时间越长,应力松弛值越大的规律。完成1个钢丝试件的高温下温度膨胀试验,得到钢丝膨胀应变随温度升高而增长的规律,初步提出钢丝高温膨胀应变计算公式。In view of the fact that creep, stress relaxation and thermal expansion are key factors on the fire resistance characteristics of prestressed structures, prestressing steel wires （standard tensile strength fptk =1770N/mm^2, low relaxation of prestress） are selected to study these factors. Creep experiments at high temperatures on 25 steel wires are carried out. Curves of creep strain and time are obtained and the creep strain model is established. It is found that creep strain will increase when any of the three factors （temperature, initial stress and time） increases. Endurance limit with creep strain at high temperatures is also presented, which shows that the difference between endurance limit and tensile strength limit increases when temperature increases. Stress relaxation experiments at high temperatures on 26 steel wires are also carried out. Curves of stress relaxation and time are obtained and the stress relaxation model is established. It is found that stress relaxation will increase when any of the three factors （temperature, initial stress and time） increases. Temperature expansion experiment at high temperature on a steel wire is also carried out.

关 键 词：预应力钢丝 高温 蠕变 应力松弛 膨胀 

分 类 号：TU511.32[建筑科学—建筑技术科学]