混凝土连续梁(板)中无粘结预应力钢筋应力增长规律研究
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摘要
把握无粘结预应力钢筋应力增长规律是准确计算无粘结预应力混凝土梁(板)刚度、裂缝开展宽度及受弯承载力的基础。首先定义了正常使用阶段无粘结预应力钢筋应力增量与有粘结非预应力钢筋增量的比值为无粘结预应力钢筋等效折减系数。然后针对无粘结部分预应力混凝土受弯构件在受荷过程中无粘结预应力钢筋不符合变形平截面假定的特点,应用等刚度法及弯矩-曲率非线性分析法,编制了可分别用于考察正常使用阶段和承载能力极限状态无粘结预应力钢筋应力增长规律的计算程序。最后基于模型试验结果和仿真分析结果,得到了无粘结预应力钢筋等效折减系数与非预应力钢筋配筋指标βs和预应力钢筋配筋指标βp的关系式,以及无粘结预应力钢筋极限应力增量与非预应力钢筋配筋指标sβ、预应力钢筋配筋指标pβ和跨高比l/h的关系式。
Comprehension of law of stress increment of unbonded tendon is the basis to accurately calculate stiffness,crack width and flexural load capacity of unbonded prestressed concrete beam and slab.Equivalent reduction coefficient of tendons was defined as the ratio of unbonded prestressed reinforcement stress increment to non-prestressed reinforcement stress increment.Considering plane-section assumption can not be applied to tendon strain in unbonded prestressed concrete flexual member subjected to loading,equivalent stiffness method and moment-curvature nonlinear analysis method are used to compile calculation programs of the law of stress increment of unbonded tendons which can be used in serviceability phase and strength limit state respectively.Based on results of model test and large numbers of simulation analysis,the relationship among equivalent reduction coefficient of tendons,non-prestressed reinforcement index βs and prestressed reinforcement index βp was formulated,and the relationship among ultimate stress increment of unbonded tendons,non-prestressed reinforcement index βs,prestressed reinforcement index βp and ratio of span to depth l/h was also formulated.
Comprehension of law of stress increment of unbonded tendon is the basis to accurately calculate stiffness,crack width and flexural load capacity of unbonded prestressed concrete beam and slab.Equivalent reduction coefficient of tendons was defined as the ratio of unbonded prestressed reinforcement stress increment to non-prestressed reinforcement stress increment.Considering plane-section assumption can not be applied to tendon strain in unbonded prestressed concrete flexual member subjected to loading,equivalent stiffness method and moment-curvature nonlinear analysis method are used to compile calculation programs of the law of stress increment of unbonded tendons which can be used in serviceability phase and strength limit state respectively.Based on results of model test and large numbers of simulation analysis,the relationship among equivalent reduction coefficient of tendons,non-prestressed reinforcement index βs and prestressed reinforcement index βp was formulated,and the relationship among ultimate stress increment of unbonded tendons,non-prestressed reinforcement index βs,prestressed reinforcement index βp and ratio of span to depth l/h was also formulated.
引文
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[3]王英,王晓东,郑文忠.预应力混凝土简支梁板中无粘结筋应力增长规律[J].吉林大学学报(工学版),2008,38(3):630-635.(Wang Ying,Wang Xiaodong,ZhengWenzhong.Lawof stress increment in unbonded tendons forconcrete simple beams and slabs[J].Journal of JilinUniversity(Engineering and Technology Edition),2008,38(3):630-635.(in Chinese))
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[2]郑文忠,郑弦,王英.预应力混凝土两跨连续梁中无粘结筋极限应力计算方法[J].建筑结构,2005,35(7):67-71.(Zheng Wenzhong,Zheng Xian,Wang Ying.Calculation of ultimate stress of unbonded tendons incontinuous prestressed concrete beam[J].BuildingStructure,2005,35(7):67-71.(in Chinese))
[3]王英,王晓东,郑文忠.预应力混凝土简支梁板中无粘结筋应力增长规律[J].吉林大学学报(工学版),2008,38(3):630-635.(Wang Ying,Wang Xiaodong,ZhengWenzhong.Lawof stress increment in unbonded tendons forconcrete simple beams and slabs[J].Journal of JilinUniversity(Engineering and Technology Edition),2008,38(3):630-635.(in Chinese))
[4]JGJ 92—2004无粘结预应力混凝土结构技术规程[S].(JGJ 92—2004 Technical specification for concretesructures prestressed with unbonded tendons[S].(inChinese))
[5]陶学康,王逸,杜拱辰.无粘结部分预应力混凝土的变形计算[J].建筑结构学报,1989,10(1):20-27.(TAOXuekang,WANG Yi,DU Gongchen.Deflection estimationfor unbonded partially prestressed concrete flexural members[J].Journal of Building Structures,1989,10(1):20-27.(in Chinese))
[6]杜拱辰,陶学康.部分预应力混凝土梁无粘结筋极限应力的研究[J].建筑结构学报,1985,6(6):2-13.(DUGongchen,TAO Xuekang.A study of the ultimate stress ofunbonded tendons in partially prestressed concrete beams[J].Journal of Building Structures,1985,6(6):2-13.(inChinese))
[7]刘丰,陈晓宝.集中荷载作用下无粘结预应力混凝土梁的试验研究[J].合肥工业大学学报,2001,24(5):880-884.(Liu Feng,Chen Xiaobao.Experimental study ofunbonded prestressed concrete beams under concentratedload[J].Journal of Hefei University of Technology,2001,24(5):880-884.(in Chinese))
[8]王晓东.混凝土受弯构件中无粘结筋应力增长规律研究[D].哈尔滨:哈尔滨工业大学,2005.(WangXiaodong.Research on law of stress increase in concreteflexural members[D].Harbin:Harbin Institute ofTechnology,2005.(in Chinese))
[9]Harajli MH.Effect of span-depth ratio on the ultimate steelstress in unbonded prestressed concrete member[J].ACIStructural Journal,1990,87(8):305-312.
[10]周威.预应力混凝土结构设计三个基本问题研究[D].哈尔滨:哈尔滨工业大学,2005.(Zhou Wei.Research onthree fundamental issues in design of prestressed concretestructures[D].Harbin:Harbin Institute of Technology,2005.(in Chinese))
[11]郑文忠.无粘结部分预应力砼矩形截面梁裂缝开展和闭合的试验研究[D].哈尔滨:哈尔滨建筑大学,1992.(Zheng Wenzhong.An experimental study on crackdeveloping and closing in free-of-bond partial prestressedbeams of rectangular section[D].Harbin:HarbinUniversity of Civil Engineering and Architecture,1992.(inChinese))
[12]解恒燕.与有粘结相协调的无粘结预应力受弯构件刚度裂缝计算[D].哈尔滨:哈尔滨工业大学,2003.(XieHengyan.Calculation of stiffness and crack of UPC flexuralmember in accordance with bonded PC flexural member[D].Harbin:Harbin Institute of Technology,2003.(inChinese))
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