地震应变率下水饱和度对混凝土动力压缩效应的影响
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摘要
为揭示地震应变率下不同含水量混凝土的力学性能变化规律,采用真空饱水设备快速制备不同水饱和度混凝土试件以消除水泥进一步水化对试验结果的影响;进行了3种应变率下(10-5s-1、10-4s-1、10-3s-1)的单轴压缩试验,测试分析了应变率和水饱和度对混凝土的应力应变曲线形态、抗压强度、弹性模量以及峰值应变的影响规律与影响机理。研究结果表明,随着应变率增加,混凝土动态抗压强度增大、弹性模量增加、而峰值应变减小;随着水饱和度增加,混凝土在静载以及动载下的抗压强度绝对值减小,但动载作用时动力强度增长因子增大;应变率越高混凝土峰值应变随水饱和度增大而减小的趋势越明显。综合考虑应变率效应以及水饱和度的影响,提出了混凝土力学性能指标的经验计算公式,与试验结果有着较好的吻合度。
To clarify the influence of water contents on the mechanical properties of concrete subjected to seismic strain rate,a vacuum water-saturated equipment was used to prepare concrete specimens with different water contents rapidly. The effect of cement secondary hydration on the rest results can be minimized by this method. Uniaxial compression tests were carried out at strain rates of 10-5,10-4 and 10-3 s-1. The effects of strain rate and water content on the stress-strain curves,compressive strength,elastic modulus and critical strain of concrete are analyzed. The obtained results show that the compressive strength and elastic modulus increase with the increase of strain rate,while the critical strain of concrete decreases. At a same strain rate,increasing water content lowers the compressive strength,but increase the dynamic increase factor under dynamic loading. Critical strain decreases more significantly with the increase of water content especially at higher strain rates. Empirical formula for the mechanical properties of concrete are proposed in this study considering the effect of strain rate as well as the water content,which has a good agreement with the test results.
To clarify the influence of water contents on the mechanical properties of concrete subjected to seismic strain rate,a vacuum water-saturated equipment was used to prepare concrete specimens with different water contents rapidly. The effect of cement secondary hydration on the rest results can be minimized by this method. Uniaxial compression tests were carried out at strain rates of 10-5,10-4 and 10-3 s-1. The effects of strain rate and water content on the stress-strain curves,compressive strength,elastic modulus and critical strain of concrete are analyzed. The obtained results show that the compressive strength and elastic modulus increase with the increase of strain rate,while the critical strain of concrete decreases. At a same strain rate,increasing water content lowers the compressive strength,but increase the dynamic increase factor under dynamic loading. Critical strain decreases more significantly with the increase of water content especially at higher strain rates. Empirical formula for the mechanical properties of concrete are proposed in this study considering the effect of strain rate as well as the water content,which has a good agreement with the test results.
引文
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[14] KLEPACZKO J R,BRARA A. An experimental method for dynamic tensile testing of concrete by spalling[J]. In?ternational Journal of Impact Engineering,2001,25(4):387-409.
[15] BRARA A,KLEPACZKO J R. Experimental characterization of concrete in dynamic tension[J]. Mechanics of Materials,2006,38(3):253-267.
[16]王海龙,李庆斌.不同加载速率下干燥与饱和混凝土抗压性能试验研究分析[J].水力发电学报,2007,26(1):84-89.
[17]闫东明,林皋,刘钧玉,等.不同环境下混凝土动态抗压特性试验研究[J].大连理工大学学报,2006,46(5):707-711.
[18] WANG H,WANG L,SONG Y,et al. Influence of free water on dynamic behavior of dam concrete under biaxial compression[J]. Construction&Building Materials,2016,112:222-231.
[19] BARTLETT F M,MACGREGOR J G. Effect of moisture condition on concrete core strengths[J]. ACI Materials Journal,1993,91(3):227-236.
[20] WANG H,JIN W,LI Q. Saturation effect on dynamic tensile and compressive strength of concrete[J]. Advances in Structural Engineering,2009,12(2):279-286.
[21] CHEN Z,HU Y,LI Q B,et al. Behavior of concrete in water subjected to dynamic triaxial compression[J]. Jour?nal of Engineering Mechanics,2010,136(3):379-389.
[22] ONOUE K,MATSUSHITA H. Reduction mechanisms of fatigue strength of concrete under compression due to permeation of liquids[J]. Construction&Building Materials,2012,37:82-92.
[23]王海龙,李庆斌.不同加载速率下饱和混凝土的劈拉试验研究及强度变化机理[J].工程力学,2007,24(2):105-109.
[24] PIHLAJAVAARA S E. A review of some of the main results of a research on the ageing phenomena of concrete:Effect of moisture conditions on strength,shrinkage and creep of mature concrete[J]. Cement&Concrete Re?search,1974,4(5):761-771.
[25] ROSSI P. A physical phenomenon which can explain the mechanical behaviour of concrete under high strain rates[J]. Materials&Structures,1991,24(6):422-424.
[26] ZHENG D,LI Q. An explanation for rate effect of concrete strength based on fracture toughness including free wa?ter viscosity[J]. Engineering Fracture Mechanics,2004,71(16):2319-2327.
[27] WANG H,LI Q. Prediction of elastic modulus and Poisson′s ratio for unsaturated concrete[J]. International Jour?nal of Solids&Structures,2007,44(5):1370-1379.
[2] BISCHOFF P H,PERRY S H. Compressive bahavior of concrete at high-strain rates[J]. Materials&Structures,1991,24(144):425-450.
[3] MALVAR L J,ROSS C A. Review of strain rate effects for concrete in tension[J]. ACI Materials Journal,1998,95(6):735-739.
[4] COOK D J,HAQUE M N. The effect of sorption on the tensile creep and strength reduction of desiccated concrete[J]. Cement&Concrete Research,1974,4(3):367-379.
[5] ROSS C A,JEROME D M,TEDESCO J W,et al. Moisture and strain rate effects on concrete strength[J]. ACI Materials Journal,1996,93(3):293-300.
[6]王海龙,李庆斌.孔隙水对湿态混凝土抗压强度的影响[J].工程力学,2006,23(10):141-144.
[7] WU S X,CHEN X D,ZHOU J K. Influence of strain rate and water content on mechanical behavior of dam con?crete[J]. Construction&Building Materials,2012,36:448-457.
[8] YAN D,LIN G. Dynamic properties of concrete in direct tension[J]. Cement&Concrete Research,2006,36(7):1371-1378.
[9] SUARIS W,SHAH S P. Properties of concrete subjected to impact[J]. Journal of Structural Engineering,1983,109(7):1727-1741.
[10] ROSSI P,MIER J G M V,BOULAY C,et al. The dynamic behaviour of concrete:influence of free water[J].Materials&Structures,1992,25(9):509-514.
[11] WATSTEIN D. Effect of straining rate on the compressive strength and elastic properties of concrete[J]. ACI Ma?terials Journal,1953,49(8):729-744.
[12] FORQUIN P,SAFA K,GARY G. Influence of free water on the quasi-static and dynamic strength of concrete in confined compression tests[J]. Cement&Concrete Research,2010,40(2):321-333.
[13] RANJITH P G,JASINGE D,SONG J Y,et al. A study of the effect of displacement rate and moisture content on the mechanical properties of concrete:Use of acoustic emission[J]. Mechanics of Materials,2008,40(6):453-469.
[14] KLEPACZKO J R,BRARA A. An experimental method for dynamic tensile testing of concrete by spalling[J]. In?ternational Journal of Impact Engineering,2001,25(4):387-409.
[15] BRARA A,KLEPACZKO J R. Experimental characterization of concrete in dynamic tension[J]. Mechanics of Materials,2006,38(3):253-267.
[16]王海龙,李庆斌.不同加载速率下干燥与饱和混凝土抗压性能试验研究分析[J].水力发电学报,2007,26(1):84-89.
[17]闫东明,林皋,刘钧玉,等.不同环境下混凝土动态抗压特性试验研究[J].大连理工大学学报,2006,46(5):707-711.
[18] WANG H,WANG L,SONG Y,et al. Influence of free water on dynamic behavior of dam concrete under biaxial compression[J]. Construction&Building Materials,2016,112:222-231.
[19] BARTLETT F M,MACGREGOR J G. Effect of moisture condition on concrete core strengths[J]. ACI Materials Journal,1993,91(3):227-236.
[20] WANG H,JIN W,LI Q. Saturation effect on dynamic tensile and compressive strength of concrete[J]. Advances in Structural Engineering,2009,12(2):279-286.
[21] CHEN Z,HU Y,LI Q B,et al. Behavior of concrete in water subjected to dynamic triaxial compression[J]. Jour?nal of Engineering Mechanics,2010,136(3):379-389.
[22] ONOUE K,MATSUSHITA H. Reduction mechanisms of fatigue strength of concrete under compression due to permeation of liquids[J]. Construction&Building Materials,2012,37:82-92.
[23]王海龙,李庆斌.不同加载速率下饱和混凝土的劈拉试验研究及强度变化机理[J].工程力学,2007,24(2):105-109.
[24] PIHLAJAVAARA S E. A review of some of the main results of a research on the ageing phenomena of concrete:Effect of moisture conditions on strength,shrinkage and creep of mature concrete[J]. Cement&Concrete Re?search,1974,4(5):761-771.
[25] ROSSI P. A physical phenomenon which can explain the mechanical behaviour of concrete under high strain rates[J]. Materials&Structures,1991,24(6):422-424.
[26] ZHENG D,LI Q. An explanation for rate effect of concrete strength based on fracture toughness including free wa?ter viscosity[J]. Engineering Fracture Mechanics,2004,71(16):2319-2327.
[27] WANG H,LI Q. Prediction of elastic modulus and Poisson′s ratio for unsaturated concrete[J]. International Jour?nal of Solids&Structures,2007,44(5):1370-1379.
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