冻融损伤后引气混凝土三轴强度准则研究

青岛海湾大桥为我国北方冰冻海域建设的第一座跨海大桥，为了有效评估冻融后承台引气混凝土的力学性能，开展了引气混凝土在冻融作用后各项基本力学性能衰减规律的试验研究。研究了海水冻融循环次数分别为0、100、200、300次的混凝土应力一应变关系，基于大型动静载伺服刚性试验机，测试受海水冻融后的混凝土应力应变曲线关系，根据混凝土应力应变曲线，总结混凝土弹性模量、抗压强度的衰减规律。根据试验结果建立了引气混凝土考虑冻融循环次数的OTTOSEN强度准则模型。试验现象表明：随着冻融循环次数的增多，混凝土轴心抗压强度、弹性模量等力学性能指标的下降程度均逐渐加大。该强度准则可为建立符合实际工程的混凝土结构冻融后抗裂设计理论提供基础资料。

Triaxial strength criterion of air entraining concrete under freeze-thaw

Qingdao Bay Bridge is the first cross sea bridge at north China frozen sea. In order to evaluate the mechanical properties of caps＇ air entraining concrete after freeze thawing, basic mechanical properties of air entraining concrete under freezing and tha- wing cycles was researched. Concrete stress and strain curve relationship was researched with the number of freeze thawing cycle of 0 times, 100 times , 200 times, 300 times. Based on the large-scale static and dynamic stiffness servo test set to test the stress-strain curves of concrete after freeze thawing. According to the concrete stress-strain curves, concrete elastic modulus and degeneration law of compressive strength are researched. OTTOSEN strength criterion model considering freezing thawing cycles for air entraining concrete is established. Tests show that the phenomenon., with the increase of the number of freeze thawing cy- cles, concrete axial compressive strength, modulus of elasticity and other mechanical properties of concrete decline gradually. This strength criterion can provide the basic data for establishing anti cracking design theory with freeze thawing.