不同初始预压应力水平混凝土给定超低温作用下有效预压性能试验研究  

EXPERIMENTAL STUDY ON EFFECTIVE PRELOADING PERFORMANCE OF CONCRETE WITH DIFFERENT INITIAL PRELOADING STRESS LEVELS AT GIVEN ULTRALOW TEMPERATURES

作　　者：时旭东[1] 韩源海 田佳伦 SHI Xu-dong;HAN Yuan-hai;TIAN Jia-un(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：《工程力学》2025年第3期157-166,共10页Engineering Mechanics

基　　金：国家自然科学基金项目(51878375)。

摘　　要：为探究预应力混凝土在超低温环境下有效预压性能的变化情况,针对不同初始预压应力水平(分别为0.2、0.3、0.4、0.5、0.6和0.7)的混凝土试件进行超低温试验,并选择两种典型的超低温情况(-80℃和-160℃)考察。试验结果显示:随初始时对预应力混凝土施加的应力水平提高,其降温点和温均点时预压应力损失率及降温段时预压应力变化比率均表现为不断地降低状,而其降温段和恒温段时预压应力变化率及恒温段时预压应力变化比率则表现为先升后降状;此外预应力混凝土达到降温点后,其在恒温阶段的预压应力损失未随着超低温程度的加深而继续增加,反而有所减少,且其减少程度与初始预压应力水平相关;相比于作用较高的超低温时,作用较低超低温时的预应力混凝土的降温点和温均点时预压应力损失率均较大。该试验的结果及其拟合公式可为LNG储罐等预应力混凝土结构的设计与风险监测提供参考。Through different initial preloading stress levels including 0.2,0.3,0.4,0.5,0.6 and 0.7 applied to concrete,the variation in the effective preloading stress of the concrete at ultralow temperatures was systematically investigated,with a focus on the influence of two typical ultralow temperatures,-80℃and-160℃.The experimental results indicate that:the preloading stress loss rate at the cooling points and the temperature uniformity points as well as its preloading stress change ratio at the cooling phase continuously decrease as the initial preloading stress level increases.While its preloading stress change rate at the cooling phase and constant temperature phase as well as its preloading stress change ratio at the constant temperature phase increase first and then decrease.After reaching the cooling point,the preloading stress loss of the prestressed concrete no longer increases but instead decreases at the constant temperature phase,regardless of whether the temperature is higher or lower,and its degree of reduction is related to the applied initial preloading stress levels.The preloading stress loss rate at the cooling points and the temperature uniformity points at a lower ultralow temperature is higher than that at a higher ultralow temperature,but its preloading stress change rate and preloading stress change ratio at the cooling phase and the constant temperature phase behave differently from its preloading stress loss rate.These results and the corresponding fitting formulas provide a reference for the design and risk monitoring of prestressed concrete structures as LNG storage tanks.

关 键 词：混凝土 初始预压应力水平 超低温 有效预压性能 降温点 温均点 

分 类 号：TU528.1[建筑科学—建筑技术科学]