基于简化分析方法的混凝土高温爆裂数值模拟

Numerical Simulation on High Temperature Cracking of Concrete based on Simplified Analysis Method

介绍了混凝土高温爆裂剥落理论及影响因素,结合国内外混凝土高温爆裂剥落研究成果提出一种简化分析方法,利用CAD-VBA二次开发生成混凝土细观几何模型,采用ADINA非线性分析软件建立热力耦合有限元模型,模拟高温下混凝土结构的爆裂剥落过程,并分析了混凝土高温爆裂剥落的主要影响因素。研究结果表明:(1)距离受火边界越近,爆裂损伤程度越高;(2)高温爆裂一般发生在距离受火边界0~5 cm范围内的水泥浆体上,混凝土结构(二维)发生爆裂剥落的面积占结构总面积的比例较小;(3)随着受火边界(面)数量、加热速率的增加,孔隙水蒸汽压力、混凝土强度等级、骨料热膨胀系数的增大,结构场外荷载的施加,混凝土结构发生爆裂剥落所需的时间减少;(4)受火边界(面)数量、结构场外荷载、混凝土强度等级对爆裂剥落的损伤程度影响较小,加热速率、孔隙水蒸汽压力及骨料热膨胀系数对爆裂剥落的损伤程度影响较大。

Theory and influencing factors on high temperature spalling cracking of concrete were introduced. A simplified analysis method was proposed combining the research results of high temperature spalling and peeling of concrete at home and abroad. The secondary development based on CADVBA was used to generate the concrete meso-geometry model,and ADINA nonlinear analysis software was used to establish thermal coupling model. The bursting and spalling process of concrete structures under high temperature was simulated by the finite element model,and the main influencing factors on high temperature spalling and spalling of concrete were analyzed. The results show that:(1)The closer to the fire boundary,the higher the burst damage;(2)The high temperature burst generally occurs in the cement ingredient within the range of 0 cm to 5 cm to the boundary of the fire,and the concrete structure(two-dimensional)bursts and peels off. The proportion of the damage area to the total area of the structure is small;(3)With the increase of fire boundaries(faces),the heating rate,the pore water vapor pressure,the concrete strength grade,the thermal expansion coefficient of the aggregate and the application of boundary load,the time required for bursting and spalling of structures reduces;(4)The number of fire boundaries(planes),external loads of the structure field,and the strength grade of concrete have little effect on the damage degree due to burst spalling. The heating rate,pore water vapor pressure,and the thermal expansion coefficient of aggregates have great influence on the damage degree of burst spalling.