(清华大学土木工程系, 北京 100084)

摘要: 通过试验探讨了初始预压应力水平对混凝土超低温下预压性能的影响,考察的应力水平为 0. 2、0. 4 及0. 6,选取的作用温度分别为-40、-80、-120℃ 及-160℃ . 结果表明,不同初始预压应力水平混凝土的预压应力损失量在各降温区间的降温阶段随降温基本上呈线性增大趋势,而其恒温阶段随恒温时间则先有所增大后呈减小甚至出现预压应力损失量恢复状,且作用的低温越低时恢复越明显;混凝土预压应力损失率在各降温区间的降温阶段随初始预压应力水平提高而降低,但恒温阶段则变得较为复杂;不同初始预压应力水平混凝土预压应力损失量均随降温点温度的降低呈现出近于线性增大的趋势,而随温均点温度的降低则呈先逐渐增大之后趋于平缓的变化态势. 结合试验数据,给出了降温点和温均点时混凝土预压应力损失量随温度变化的拟合关系式.

关键词: 预应力混凝土; 超低温; 预压性能; 预压应力损失

中图分类号:TU528. 1 文献标志码:A 文章编号:1002-848X(2023)05-0041-06

DOI:10. 19701 / j. jzjg. 20201622

Experimental study on influence of initial preloading stress levels on preloading performance of concrete exposed to ultralow temperature

SHI Xudong, HAN Daquan, LI Yaqiang

(Department of Civil Engineering, Tsinghua University, Beijing 100084, China)

Abstract: The effect of initial preloading stress levels ( IPSLs) on the preloading performance of concrete exposed toultralow temperature was discussed through experiment. The examining initial preloading stress levels acting on specimenconcrete are 0. 2, 0. 4 and 0. 6, and the corresponding temperatures including - 40, - 80, - 120℃ and - 160℃ arerespectively exerted. The test results show that the preloading stress loss of concrete with different IPSLs increases linearlywith the decrease in temperature during the cooling stage of each ultralow temperature range. However, the preloadingstress loss of concrete increases first and then decreases or even recovers with increase in the time during the constanttemperature stage, and the lower the exerted lower limit temperature, the more obvious the recovery. The preloading stressloss rate of concrete decreases with the increase in the IPSL during the cooling stage of each ultralow temperature range, butit will become complicated during the constant temperature stage. The preloading stress loss of concrete with different IPSLsshows a nearly linear increase trend with the decrease in temperature at the cooling target point. But it will have a differentchanging trend which increases first and then flattens at the temperature uniformity target point. According to the test data,the preloading stress loss of concrete with temperature at the cooling target point and the temperature uniformity target pointwas given.

Keywords:prestressed concrete; ultralow temperature; preloading performance; preloading stress loss

∗国家自然科学基金项目(51878375).

第一作者:时旭东,博士,教授,主要从事超低温混凝土性能研究,Email: shixd@ mail. tsinghua. edu. cn.

[引用本文] 时旭东,韩大全,李亚强. 初始预压应力水平对混凝土超低温下预压性能影响试验研究[ J]. 建筑结构,2023,53( 5):41-46. SHI Xudong,HAN Daquan,LI Yaqiang. Experimental study on influence of initial preloadingstress levels on preloading performance of concrete exposed to ultralow temperature[J]. Building Structure,2023,53(5):41-46.