考虑翼缘影响的钢筋混凝土T梁抗剪承载力
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摘要
针对现行规范忽略翼缘的抗剪提高作用和过于低估混凝土T梁抗剪承载力的问题,探讨了T形截面混凝土梁剪力传递机理,基于有效抗剪区域思想提出了腹板抗剪有效宽度计算方法,进而建立了考虑翼缘影响的混凝土T梁抗剪承载力理论计算式.该公式形式简单,物理意义明确,可退化为矩形梁抗剪承载力公式,可以较好地反应混凝土强度、剪跨比、纵筋率、翼缘宽度等主要因素对抗剪承载力的影响规律.采用157片混凝土T梁试验数据对理论计算式进行验证,并与国内外规范进行对比.结果表明,该公式可以很好预测混凝土T梁抗剪承载力,抗剪承载力计算值与试验值比值均值为1.012,标准差为0.268.
The current codes ignore the improvement on shear strength by flange, resulting in an underestimation on the shear strength of concrete T-beams. The shear transfer mechanism was discussed. The calculation method for the effective web width was established based on the concept of the effective shear funnel and the shear strength formula was proposed subsequently. The proposed shear strength formula is in a simple expression with clear physical significance. It can be degraded into the shear strength formula for reinforced concrete beams with rectangular cross-section and takes several main factors into account, such as concrete strength, shear span-to-depth ratio, longitudinal reinforcement ratio and flange width. 157 reinforced concrete T-beams were used to evaluate the proposed formula and compared with the specifications. The results indicate that the proposed shear strength formula is applicable to the prediction of the shear strength of reinforced concrete T-beams. The mean value of the ratios of the computational values to the experimental results is 1.012 with a standard deviation of 0.268.
The current codes ignore the improvement on shear strength by flange, resulting in an underestimation on the shear strength of concrete T-beams. The shear transfer mechanism was discussed. The calculation method for the effective web width was established based on the concept of the effective shear funnel and the shear strength formula was proposed subsequently. The proposed shear strength formula is in a simple expression with clear physical significance. It can be degraded into the shear strength formula for reinforced concrete beams with rectangular cross-section and takes several main factors into account, such as concrete strength, shear span-to-depth ratio, longitudinal reinforcement ratio and flange width. 157 reinforced concrete T-beams were used to evaluate the proposed formula and compared with the specifications. The results indicate that the proposed shear strength formula is applicable to the prediction of the shear strength of reinforced concrete T-beams. The mean value of the ratios of the computational values to the experimental results is 1.012 with a standard deviation of 0.268.
引文
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[6] American Concrete Institute.ACI 318-14 Building code requirements for structural concrete and commentary [S].Farmington Hills,Mich,USA:American Concrete Institute,2011.
[7] Federal Institute of Technology Lausanne-EPFL.fib model code for concrete structures 2010[S].Berlin:Ernst & Sohn,2013.
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[13] Thamrin R,Tanjung J,Aryanti R,et al.Shear strength of reinforced concrete T-beams without stirrups[J].Journal of Engineering Science and Technology,2016,11(4):548-562.
[14] Kotsovos M D,Bobrowski J,Eibl J.Behaviour of reinforced concrete T-beams in shear[J].Structural Engineer,Part B,1987,65:1-10.
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[17] Bourget S,El-Saikaly G,Chaallal O.Behavior of reinforced concrete T-beams strengthened in shear using closed carbon fiber-reinforced polymer stirrups made of laminates and ropes[J].ACI Structural Journal,2017,114(5):1087-1098.DOI:10.14359/51700786.
[18] El-Saikaly G,Chaallal O,Benmokrane B.Fatigue assessment of shear-strengthened RC T-beams with externally bonded CFRP closed stirrups[J].Journal of Composites for Construction,2018,22(6):04018049.DOI:10.1061/(asce)cc.1943-5614.0000885.
[19] Foster R M,Brindley M,Lees J M,et al.Experimental investigation of reinforced concrete T-beams strengthened in shear with externally bonded CFRP sheets[J].Journal of Composites for Construction,2016,21(2):04016086.DOI:10.1061/(asce)cc.1943-5614.0000743.
[20] Al-Alusi A F.Diagonal tension strength of reinforced concrete T-beams with varying shear span[J].ACI Journal,1957,53(5):1067-1077.DOI:10.14359/11572.
[21] Cerruti L M,Marti P.Staggered shear design of concrete beams:Large-scale tests[J].Canadian Journal of Civil Engineering,1987,14(2):257-268.DOI:10.1139/l87-038.
[22] Ferguson P M.Some implications of recent diagonal tension tests[J].ACI Journal,1956,53:157-172.DOI:10.14359/11507.
[23] Kani G.Kani on shear in reinforced concrete[M].Toronto,Canada:University of Toronto,1979.
[24] Lyngberg B S.Ultimate shear resistance of partially prestressed reinforced concrete I-beams[J].ACI Journal,1976,73(4):214-222.DOI:10.14359/11068.
[25] Rangan B V.Web crushing strength of reinforced and prestressed concrete beams[J].ACI Structural Journal,1991,88(1):12-16.DOI:10.14359/3050.
[26] Technical University of Denmark.Shear tests on 12 reinforced concrete T-beams[R].Denmark:Sorensen H C,1974.
[27] Placas A.Shear failure of reinforced concrete beams [D].London:University of London,1969.
[28] 沈殷.体外预应力混凝土桥梁抗剪承载力[D].上海:同济大学,2004.Shen Y.Study on the shear strength of externally prestressed concrete bridges[D].Shanghai:Tongji University,2004.(in Chinese)
[2] Qi J N,Ma Z J,Wang J Q,et al.Post-cracking shear strength and deformability of HSS-UHPFRC beams[J].Structural Concrete,2016,17(6):1033-1046.DOI:10.1002/suco.201500191.
[3] 戚家南,王景全,吕志涛.体外预应力混凝土梁受剪承载力计算方法研究[J].建筑结构学报,2015,36(1):92-97.DOI:10.14006/j.jzjgxb.2015.01.012.Qi J N,Wang J Q,Lü Z T.Calculation method of shear strength of externally prestressed concrete beams[J].Journal of Building Structures,2015,36(1):92-97.DOI:10.14006/j.jzjgxb.2015.01.012.(in Chinese)
[4] Qi J N,Ma Z J,Wang J Q.Shear strength of UHPFRC beams:Mesoscale fiber-matrix discrete model[J].Journal of Structural Engineering,2017,143(4):04016209.DOI:10.1061/(asce)st.1943-541x.0001701.
[5] 戚家南.混凝土(RC&PC&EPC)梁桥抗剪承载力计算方法的理论与试验研究[D].南京:东南大学,2013.Qi J N.Theoretical and experimental study of shear strength for RC&PC&EPC bridge[D].Nanjing:Southeast University,2013.(in Chinese)
[6] American Concrete Institute.ACI 318-14 Building code requirements for structural concrete and commentary [S].Farmington Hills,Mich,USA:American Concrete Institute,2011.
[7] Federal Institute of Technology Lausanne-EPFL.fib model code for concrete structures 2010[S].Berlin:Ernst & Sohn,2013.
[8] 中华人民共和国住房和城乡建设部.GB 50010—2010混凝土结构设计规范[S].北京:中国建筑工业出版社,2010.
[9] Tureyen A K,Wolf T S,Frosch R J.Shear strength of reinforced concrete T-beams without transverse reinforcement[J].ACI Structural Journal,2006,103(5):656-663.
[10] Zararis I P,Karaveziroglou M K,Zararis P D.Shear strength of reinforced concrete T-beams[J].ACI Structural Journal,2006,103(5):693-700.
[11] Taplin G,Al-Mahaidi R.An experimental investigation of shear critical T-beams[C]// Proc 3rd Structural Speciality Conf.London,ON,Canada:Canadian Society for Civil Engineering,2000.
[12] Placas A,Regan P E.Shear failure of reinforced concrete beams[J].ACI Journal,1971,68(10):763-773.
[13] Thamrin R,Tanjung J,Aryanti R,et al.Shear strength of reinforced concrete T-beams without stirrups[J].Journal of Engineering Science and Technology,2016,11(4):548-562.
[14] Kotsovos M D,Bobrowski J,Eibl J.Behaviour of reinforced concrete T-beams in shear[J].Structural Engineer,Part B,1987,65:1-10.
[15] Tureyen A K,Frosch R J.Concrete shear strength:Another perspective[J].ACI Structural Journal,2003,100(5):609-615.DOI:10.14359/12802.
[16] Kotsovou G M,Cotsovos D M.Shear failure criterion for RC T-beams[J].Engineering Structures,2018,160:44-55.DOI:10.1016/j.engstruct.2017.12.044.
[17] Bourget S,El-Saikaly G,Chaallal O.Behavior of reinforced concrete T-beams strengthened in shear using closed carbon fiber-reinforced polymer stirrups made of laminates and ropes[J].ACI Structural Journal,2017,114(5):1087-1098.DOI:10.14359/51700786.
[18] El-Saikaly G,Chaallal O,Benmokrane B.Fatigue assessment of shear-strengthened RC T-beams with externally bonded CFRP closed stirrups[J].Journal of Composites for Construction,2018,22(6):04018049.DOI:10.1061/(asce)cc.1943-5614.0000885.
[19] Foster R M,Brindley M,Lees J M,et al.Experimental investigation of reinforced concrete T-beams strengthened in shear with externally bonded CFRP sheets[J].Journal of Composites for Construction,2016,21(2):04016086.DOI:10.1061/(asce)cc.1943-5614.0000743.
[20] Al-Alusi A F.Diagonal tension strength of reinforced concrete T-beams with varying shear span[J].ACI Journal,1957,53(5):1067-1077.DOI:10.14359/11572.
[21] Cerruti L M,Marti P.Staggered shear design of concrete beams:Large-scale tests[J].Canadian Journal of Civil Engineering,1987,14(2):257-268.DOI:10.1139/l87-038.
[22] Ferguson P M.Some implications of recent diagonal tension tests[J].ACI Journal,1956,53:157-172.DOI:10.14359/11507.
[23] Kani G.Kani on shear in reinforced concrete[M].Toronto,Canada:University of Toronto,1979.
[24] Lyngberg B S.Ultimate shear resistance of partially prestressed reinforced concrete I-beams[J].ACI Journal,1976,73(4):214-222.DOI:10.14359/11068.
[25] Rangan B V.Web crushing strength of reinforced and prestressed concrete beams[J].ACI Structural Journal,1991,88(1):12-16.DOI:10.14359/3050.
[26] Technical University of Denmark.Shear tests on 12 reinforced concrete T-beams[R].Denmark:Sorensen H C,1974.
[27] Placas A.Shear failure of reinforced concrete beams [D].London:University of London,1969.
[28] 沈殷.体外预应力混凝土桥梁抗剪承载力[D].上海:同济大学,2004.Shen Y.Study on the shear strength of externally prestressed concrete bridges[D].Shanghai:Tongji University,2004.(in Chinese)