高溫下高強混凝土導熱系數反演及其變異性

肖建莊+李志衛

建筑科學與工程學報2014年文章編號：16732049(2014)01004406

收稿日期：20140119

基金項目：國家重點基礎研究發展計劃（“九七三”計劃）項目（2012CB719703）

作者簡介：肖建莊（1968），男，山東沂南人，教授，博士研究生導師，工學博士，

摘要：為研究高溫下高強混凝土（HSC）的導熱系數，對6種工況下的高強混凝土試件進行了高溫試驗，得到不同高溫下高強混凝土的內部溫度場?；谝痪S熱傳導理論和實測溫度，利用差分原理推導的離散溫度點表示的導熱系數計算公式，反演分析了高溫下高強混凝土的導熱系數，并分析了高溫下導熱系數的變化規律及變異性；最后建立了高溫下高強混凝土導熱系數的計算公式。研究結果表明：高溫下高強混凝土內部的溫度變化可以分為3個階段，高溫下高強混凝土的導熱系數隨著溫度的升高而逐漸降低，但是在200 ℃~400 ℃時出現反彈現象，500 ℃后趨于穩定；利用所建立的導熱系數公式計算的溫度場與相關文獻中試驗結果吻合較好。

關鍵詞：高強混凝土；高溫；導熱系數；反演；變異性；擬合曲線

中圖分類號：TU111文獻標志碼：A

Backanalysis and Variability of Thermal Conductivity of Highstrength

Concrete Under High TemperaturesXIAO Jianzhuang, LI Zhiwei

（Department of Building Engineering, Tongji University, Shanghai 200092, China）Abstract: In order to study the thermal conductivity of highstrength concrete (HSC) under high temperatures, the high temperature experiments for six types of HSC specimens were conducted and the internal temperature fields of HSC under different high temperatures were recorded. The calculation formulae of thermal conductivities of HSC under high temperatures were derived based on the backanalysis of one dimension heat conduction theory, measured temperatures and the equation for thermal conductivity expressed by discrete temperature values derived by difference principles. Meanwhile, the changing regularities and variability of the thermal conductivity under high temperatures were analyzed. At last, the calculation formulae for the thermal conductivity of HSC under high temperatures were established. The study results show that the internal temperature variation of HSC under high temperatures can be divided into three phases. The thermal conductivity under high temperatures of HSC will decrease with the increasing of temperature. But the thermal conductivity rebounds at 200 ℃400 ℃ and tends to stabilize when the temperature is beyond 500 ℃. The temperature fields calculated by the proposed formulae are in good agreement with those of other test results in relative literature.

Key words: highstrength concrete; high temperature; thermal conductivity; backanalysis; variability; fitted curve

0引言

由于高強混凝土（HSC）比普通混凝土具有更高的強度和更好的耐久性，近年來在土木工程中得到了大量應用［1］；同時，很多混凝土工程需要考慮抗火防災，因而HSC的抗火性能越來越引起人們的重視。導熱系數是研究火災中混凝土結構高溫反應的基礎，各國專家對導熱系數進行了測定［24］，這些導熱系數都是通過對普通混凝土的試驗所得。針對HSC導熱系數的研究較少，只有文獻［5］，［6］中分別通過試驗和理論推導對HSC的導熱系數進行了分析，而2篇文獻所研究的結果存在一定的差異。……