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（清華大學(xué)土木工程系，北京 100084）

［摘要］已有的混凝土受熱力學(xué)性能研究重點(diǎn)集中于500℃以上的高溫區(qū)段，小于500℃的亞高溫區(qū)段的混凝土強(qiáng)度則直接按常溫處理，這不符合實(shí)際溫度作用的受力情況。長期處于亞高溫作用下的混凝土結(jié)構(gòu)也需要了解其材料受力性能的變化規(guī)律。通過亞高溫區(qū)段混凝土的受壓強(qiáng)度試驗(yàn)，考察了不同亞高溫及溫度持續(xù)時(shí)間對(duì)其的影響。結(jié)果表明，不同溫度持續(xù)時(shí)間的混凝土受壓強(qiáng)度隨溫度升高的變化趨勢相似，在100～250℃波動(dòng)較大，且在100℃附近形成一個(gè)強(qiáng)度的低谷，250℃后則呈急劇下降趨勢。而當(dāng)試件溫度分布均勻后，溫度持續(xù)時(shí)間對(duì)混凝土受壓強(qiáng)度的影響很小。通過試驗(yàn)還給出了亞高溫下混凝土受壓強(qiáng)度的計(jì)算公式。

［關(guān)鍵詞］混凝土；亞高溫；持續(xù)時(shí)間；受壓強(qiáng)度；試驗(yàn)

中圖分類號(hào)：TU528.1文獻(xiàn)標(biāo)識(shí)碼：A文章編號(hào)：1002-848X(2011)08-0106-04

Experimental study on compressive strength of concrete under lasting sub-high temperature

Shi Xudong, Liu Chao, Li Liang, Xing Wanli

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

Abstract:Existing researches on behaviors of heated concrete are mainly focused on the high temperature range above 500℃. The compressive strength of concrete under sub-high temperature (<500℃) is only simply taken as that at room temperature， and  this does not accord with its actual mechanical properties. It is more important to investigate the mechanical properties of concrete in the structures subjected to long-term sub-high temperature. The influences of sub-high temperature and its lasting time on the concrete compressive strength were investigated based on experiments. It is shown that the concrete compressive strength with different temperature lasting time has a similar changing trend. There exists a strength fluctuation from 100℃ to 250℃ with a concave around 100℃ and sharp decrease after 250℃. Temperature lasting time has little effect on the compressive strength after the temperature distribution becomes uniform. A calculation formula of strength of concrete subjected to sub-high temperature was presented.

Keywords:concrete; sub-high temperature; lasting time; compressive strength; experiment

*國家自然科學(xué)基金資助項(xiàng)目（51078204）。

作者簡介：時(shí)旭東，博士，Email: shixudong@mails.tsinghua.edu.cn。

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