不同低温作用下给定含水率预应力混凝土有效预压性能试验研究  

Experimental Study on Effective Preloading Performance of Prestressed Concrete with Given Water Content at Different Ultralow Temperatures

作　　者：时旭东[1] 韩源海 田佳伦 SHI Xudong;HAN Yuanhai;TIAN Jiaun(Department of Civil Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学土木工程系,北京100084

出　　处：《工业建筑》2023年第6期181-186,193,共7页Industrial Construction

基　　金：国家自然科学基金项目(51878375)。

摘　　要：通过正常含水率预应力混凝土经历0,-20,-40,-60,-80,-100,-120,-140,-160℃的低温作用试验,探讨不同低温作用下预应力混凝土的预压应力变化规律,并由较低和较高低温作用的试验给出较高含水率情况下对其影响的差异性。结果表明:随作用低温的降低,预应力混凝土在降温点和温均点时预压应力损失率均呈先快速后缓慢增加的变化趋势;而其降温段和恒温段的预压应力变化率有所不同,它们分别呈先快速增加后基本线性减小和先快速后逐渐缓慢减小的变化趋势。作用低温较低时,达降温点后的恒温阶段预应力混凝土的预压应力损失不再增加,且还有所恢复。含水率对预应力混凝土的预压应力损失率和预压应力变化率将产生较为复杂的影响,并与作用的低温密切相关。这些试验结果可为低温储罐类预应力混凝土结构的设计和安全评估提供参考。Through the experiments of concrete with normal water content experiencing cryogenic temperatures of 0 ℃,-20 ℃,-40 ℃,-60 ℃,-80 ℃,-100 ℃,-120 ℃,-140 ℃ and-160 ℃,the changing regularity of the preloading stress of prestressed concrete under different cryogenic temperatures was discussed,and the difference of the effect of higher water content on it was given by the experiments from lower and higher cryogenic temperature actions.The test results showed that the preloading stress loss rate of prestressed concrete at the cooling target points and the temperature uniformity target points increased rapidly first and then slowly with the decreased in the exerted cryogenic temperatures.But its preloading stress changing rate at the cooling stages was different from that at the constant temperature stages.The former showed a trend of rapid increase first and then basically linear decrease,and the latter showed a trend of rapid first and then gradually slow decrease.The loss of preloading stress of the prestressed concrete no longer increased but recovered at the constant temperature stages after reaching the cooling target points.The influence of water content on the preloading stress loss rate and the preloading stress changing rate of prestressed concrete was complex,and it was related to the exerted cryogenic temperatures.These results could provide a reference for the design and safety evaluation of prestressed concrete structures as LNG storage tanks.

关 键 词：预应力混凝土 超低温 含水率 预压应力损失 降温点 温均点 

分 类 号：TU528[建筑科学—建筑技术科学]