冻融循环与氯离子侵蚀后预应力混凝土梁受弯性能

Flexural behaviors of prestressed concrete beams after freeze-thaw cycles and chloride penetration

为研究预应力钢筋混凝土结构的耐久性,在预应力度分别为0.35、0.52和0.62的预应力混凝土梁试件分别经历50、75次冻融循环作用和氯离子溶液腐蚀后,对其进行静力受弯试验。研究表明:动弹性模量随冻融循环次数的增加下降较快,预应力度高的试件动弹性模量损失较小;预应力度分别为0.35、0.52和0.62的试件,在冻融循环75次后的开裂荷载较冻融循环50次的试件分别下降6.9%、6.7%、5.7%,极限荷载分别下降14.7%、17.5%、11.6%;冻融循环50次后,预应力度为0.52和0.62的试件较预应力度为0.35试件的开裂荷载分别高20%、17.85%,极限荷载分别高21.4%、8.7%;冻融循环75次后,预应力度为0.52和0.62的试件较预应力度为0.35试件的开裂荷载分别高23.8%、19.0%,极限荷载分别高24.1%、19.4%;氯离子侵蚀在短期内对试件极限承载力影响较小。

In order to study the durability of prestressed concrete structures,6 prestressed concrete beams with partial prestressing ratios of 0. 35,0. 52 and 0. 62 are tested by static flexural experiments after experiencing freeze-thaw cycles and chloride penetration for 50 and 75 times. The results show that the concrete dynamic elastic modulus decrease fast with the increase of the freeze-thaw cycle number,and the dynamic elastic modulus of tested specimens with the high partial prestressing ratios decrease less; for components with prestressing ratios of 0. 35,0. 52 and 0. 62,comparing the results after 50 times freeze-thaw cycles with the results after 75 times freeze-thaw cycles,the cracking loads decrease 6. 9%,6. 7% and 5. 7% respectively and the ultimate loads decrease 4. 7%,17.5% and 11. 6% respectively; after 50 times freeze-thaw cycles,the cracking loads of components with prestressing ratios of 0. 52 and 0. 62 are higher than those of 0. 35 by 20%,17. 85% respectively,and the ultimate loads are higher by 21. 4%,8. 7% respectively; after 75 times freeze-thaw cycles,the cracking loads of components with prestressing ratios of 0. 52 and 0. 62 are higher than those of 0.35 by 23. 8%,19. 0% respectively,and the ultimate loads are higher by 24. 1%,19. 4% respectively;chloride penetration effects the bearing capacity of the components less.