太阳辐射作用下钢管混凝土拱不均匀温度场及其引起的脱空分析与试验研究

为厘清太阳辐射作用下钢管混凝土拱肋内部的不均匀时变温度场，剖析其对钢管混凝土脱空效应的影响机制，并为钢管混凝土拱桥的脱空病害防治奠定理论基础，依托受日照辐射较强的贵州香火岩特大跨钢管混凝土拱桥实际工程，建立考虑钢管与混凝土界面接触关系的精细化温度-应力耦合数值模型；基于ASHRAE晴空模型及温度场计算理论，开展了钢管混凝土拱肋日照辐射不均匀时变温度场分析，揭示了钢管混凝土拱肋横截面的温度分布规律及其随时间的变化规律，并给出了计算钢管混凝土横截面温度梯度的近似公式；结合脱空的应力判别标准，计算出了拱肋横截面沿环向不同位置处的脱空高度，进而明确了钢管混凝土拱肋的横截面脱空分布模式；基于诱导振动理论，选取主要受温度影响而产生脱空的拱段，开展了钢管混凝土拱桥脱空检测试验研究，并与理论分析进行对比，验证了理论分析的可靠性。研究结果表明：日照辐射作用下，钢管混凝土截面温度场在时间、空间分布上均呈高度非线性，核心混凝土温度变化滞后于外包钢管，钢管与核心混凝土的最大温差超过25℃；日照不均匀温差引起的界面拉应力达到1.4~1.5 MPa，导致钢管混凝土环向脱空高度达到0.11~0.13 mm；基于诱导振动法的钢管混凝土拱肋脱空检测方法可识别出脱空的可能性，并发现太阳辐射作用使钢管混凝土的脱空程度略有增强。

Analysis and Experimental Study of Uneven Temperature Fields in Concrete-filled Steel Tubular Arches Under Solar Radiation and Its Void Effect

In order to clarify the uneven time-varying temperature field inside the concrete-filled steel tube( CFST) arch rib under the action of solar radiation,analyze its influence on the void effect of the CFST,and lay a theoretical foundation for the prevention of CFST voids,a refined temperature-stress coupling numerical model considering the contact relationship between the steel tube and concrete interface was established using the actual Guizhou Xianghuoyan extra-large CFST arch bridge project that is exposed to intense solar radiation. Based on the ASHRAE clear sky model and temperature field calculation theory,an analysis of the time-varying temperature field of the CFST arch rib under solar radiation was carried out. Moreover,the temperature distribution of the CFST arch rib and its variation with time was revealed,and the approximate formula for calculating the temperature gradient of the CFST section is provided. Combined with the stress criterion of the void,the rib section was calculated along with the void height at different positions in the radial direction. Furthermore,the cross-sectional void distribution pattern of the CFST arch rib was clearly defined. Based on the induced vibration theory,the arch sections,which were mainly affected by the temperature and voids,were selected,and the test of the CFST bridge was carried out. Along with the theoretical analysis,the reliability of the theoretical analysis was verified. Research indicates that under the action of solar radiation,the temperature field of the CFST section is highly nonlinear with respect to time and space distribution. The core concrete temperature lags behind that of the outer steel tube,and the maximum temperature difference between the steel tube and the core concrete exceeds 25 °C. Additionally,the interface tensile stress,caused by the uneven temperature difference of solar radiation reaches 1. 4-1. 5 MPa,in which causes the hoop void height of the CFST approaching 0. 11-0. 13 mm. The detection method of the CFST arch ribs,based on the induced vibration method,can help identify the possibility of voids and indicates that the solar radiation slightly increases the void degree in the CFST.