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LONG-TERM DEFLECTION OF HIGH-STRENGTH LIGHTWEIGHT AGGREGATE CONCRETE BEAMS
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摘要: 进行了28d强度为60.8MPa和64.4MPa的3根高强轻骨料混凝土梁近1年的长期荷载试验。试验结果表明,在持续荷载作用下,轻骨料混凝土梁的长期变形在初期发展较快,后期发展较慢;受压区配筋能够约束梁的长期变形发展,配筋率越高,长期变形越小。结合编制的混凝土结构长期性能分析程序,基于材料收缩和徐变试验数据,对试验梁进行了计算分析,计算值与试验结果吻合较好。还分别采用几个规范方法对长期挠度增大系数进行了分析,结果表明,ACI318和ACI435方法与试验结果比较吻合,而《混凝土结构设计规范》(GB 50010-2002)与《轻骨料混凝土桥梁技术规程》(报批稿)的计算结果对试验偏于不安全。Abstract: Three high-strength lightweight aggregate concrete (LWAC) beams were experimented for long-term deflections,which lasted for nearly 1 year, with the average 28-day compressive strength 601 8MPa and 6414MPa. From the test results it is observed that long-term deflections developed quickly at early ages and reinforcement ratio for compression steel had a significant effect on time-dependent deflections. Finite element methods had been developed to account for time-dependent deflections of reinforced concrete members and a good agreement was achieved. It isfound that ACI318 and ACI435methodshad resulted in good estimates for the time-dependent deformation and the design methods of current Chinese codes may be unsafe.
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[2] Reichard T W.Creep and Drying Shrinkage of Lightweight and NormalWeight Concretes.NBS Monograph 74,U.S.Department of Commerce,1964 Best C H,Polivka M.Creep of Lightweight Concrete.Magazine of Concrete Research,1959,11 (33):129-134 [3] Stevens R F.Deflection of Reinforced Concrete Beams.The Institution of Civil Engineers,Proceedings Part 2,1972(53):207-224 [4] 刚度裂缝专题组.钢筋轻骨料混凝土受弯构件刚度的试验研究.建筑结构,1983(1):16-21 [5] 丁大钧.钢筋混凝土构件抗烈度裂缝和刚度.南京:南京工学院出版社,1986 [6] CEB-FIP.CEB-FIP Model Code 1990.London:1991 [7] JTG D62-2004 公路钢筋混凝土及预应力混凝土桥涵设计规范 [8] ACI Committee 318.Building Code Requirements for Reinforced Concrete.American Concrete Institute,1989 [9] ACI Committee 435.Control of Deflection in Concrete Structures.American Concrete Institute,1995 [10] 轻骨料混凝土桥梁技术规程(报批稿).北京:中国建筑科学研究院,2002 [11] GB 50010-2002 混凝土结构设计规范 -
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