【作者】 毛达岭；

【导师】 刘立新；

【作者基本信息】 郑州大学 ， 结构工程， 2008， 博士

【摘要】 混凝土结构是我国目前应用最广泛的建筑结构形式。但与国外相比,我国混凝土结构用钢筋的强度普遍低1～2个等级,直接造成构件配筋密集,施工困难,钢筋用量过大,相应能源和资源消耗偏高,与我国目前提倡的“可持续发展战略”背道而驰。近年来,我国冶金行业通过添加钒等微合金元素,新开发出了强度标准值为500MPa的热轧HRB500级钢筋,并又通过控温控轧技术,开发出不添加或少添加微量元素的500MPa级超细晶粒钢筋。其中HRB500级钢筋已列入我国《混凝土结构用钢筋标准》(GB1499-1998),但由于缺乏全面系统的科研工作,尤其基础性试验研究严重不足,《混凝土结构设计规范》(GB50010-2002)尚未列入500MPa级钢筋,直接影响了500MPa级钢筋在实际工程中的推广应用。本文针对500MPa级钢筋在受压构件中的应用,共进行了32个轴心受压和9个偏心受压500MPa级钢筋混凝土柱受力性能的试验研究,根据试验结果进行了轴压柱的混凝土应力应变曲线分析和偏压柱的数值模拟,提出了500MPa级钢筋用于混凝土结构受压构件的设计建议,并依据上述建议进行了HRB500级钢筋的试点工程应用分析。主要内容如下:1.通过500MPa级钢筋混凝土轴压柱试验,分析了混凝土强度、纵向钢筋配筋率、配箍情况和纵筋强度对轴压受力变形性能的影响,探讨了混凝土强度和纵筋配筋率与混凝土受压峰值应变和峰值应力的变化规律,研究表明:①随着混凝土强度、纵筋配筋率和箍筋体积配箍率的提高,轴压柱的混凝土峰值应变均有明显增大并可超过0.002,在常用的受压构件纵筋配筋率范围内以及规范构造配箍条件下,混凝土峰值压应变在0.0022～0.0026之间,500MPa级钢筋在受压构件中能充分发挥其抗压强度;②当钢筋和混凝土强度分别取实测平均值(f_y约为524MPa)和标准值时,根据现行规范公式对轴压承载力进行了计算分析,试验值与计算值之比分别为1.08和1.24,计算结果偏于安全,具有一定的安全储备。2.根据对轴压柱混凝土应力应变曲线的试验结果,通过对曲线特征点的分析和对规范附录C混凝土受压应力应变曲线的改进,提出了综合考虑纵筋和配箍影响的混凝土峰值压应力和峰值压应变的计算公式和应力应变曲线方程,计算结果与试验结果符合较好,可作为混凝土结构和构件非线性分析的参考。3.通过500MPa级钢筋混凝土偏压柱试验,分析了偏心距和纵筋配筋率对偏压柱侧向挠度、受压边缘混凝土应变和纵向钢筋应变的影响,其受力性能与普通钢筋混凝土偏压柱一致,当钢筋和混凝土强度取实测平均值(f_y约为516MPa)时,按我国现行规范公式计算偏压柱承载力,试验值与计算值之比为1.18,计算结果偏于安全,具有一定的安全储备。4.在偏压柱试验研究的基础上,编写了基于Matlab的偏压柱非线性分析程序,进行了纵筋分别采用500MPa级和HRB335级钢筋的偏压柱数值模拟试验,分析了偏心距、长细比、混凝土强度和纵筋配筋率对二阶效应影响,并与中国、美国和欧洲规范公式计算结果进行了对比分析,研究表明:500MPa级钢筋混凝土偏压柱的二阶效应变化规律与普通钢筋混凝土柱相同,中国、美国和欧洲规范的二阶效应公式计算结果与模拟试验结果基本一致,500MPa级钢筋混凝土偏压柱二阶效应可采用我国现行规范公式进行计算,且与采用HRB335级钢筋的偏压柱具有大致相同的安全度。5.基于上述试验研究和分析,提出了500MPa级钢筋用于受压构件的设计强度取值(f_y=f_yk/r_s=500/1.1≈450MPa)和设计建议,进行了国内首个采用HRB500钢筋的试点工程的设计,并与采用HRB335和HRB400钢筋的用量进行了对比分析,研究表明:①采用500MPa级高强钢筋替代传统钢筋在一定条件下可明显减少钢筋用量,可改善目前框架结构中梁、柱节点和框架柱中钢筋拥挤的现象,提高工程质量,取得较好的社会经济效益;②在工程结构中要更为有效地推广应用500MPa级钢筋,还应改进和完善现行规范裂缝宽度和最小配筋率的计算方法或规定,为500MPa级高强钢筋列入我国《混凝土结构设计规范》提供了工程依据。本文的研究得到了国家自然科学基金(项目批准号:50578148)和国家863计划(项目编号:2004AA33G050)的资助。更多还原

【Abstract】 Concrete structure is the most widespread structural style at present in our country. But strength grade of steel bar applied in concrete structure in our country is universally 1-2 grades lower than that in overseas.This directly causees crowded reinforcing bars in concrete members,construction difficulty,oversized steel bar amount,and the high energy and resources consumption,which run counter to "the sustainable development" policy our goverment advocates at present.In recent years in our metallurgical industry,HRB500 steel bar was developed by rare elements（such as vanadium et） addition,and 500MPa level ultra-fine crystal grain steel bar was newly exploited out through temperature and rolling conformity technology,which has no or fewer rare element.HRB500 steel bar has been included in " Hot rolled ribbed steel bars for the reinforcement of concrete "（GB1499-1998）, but because the lack of comprehensive and systematic scientific effort,especially seriously insufficiency of fundamental experiment study,500MPa grade steel bar has not been included in the "Concrete structure Design Code"（GB50010-2002）,which immediately influence the application of 500MPa grade steel bar in actual project.In this paper,for the purpose of 500MPa grade steel bar application in concrete compression members,a total of 32 axially compressed and nine eccentrically compressed 500 MPa grade steel bar reinforced concrete column tests were conducted, compression performance study was carried out,axial compression stress-strain curve and numerical simulation of eccentrically compressed column were analyzed according to test results,the design suggestion of 500 MPa grade steel bar used in reinforced concrete compression member was proposed,and the application analysis of HRB500 steel bar pilot project was completed in accordance with the above proposal.The main content is as follows:1.Through test of axially compressed concrete column reinforced with 500 MPa grade steel bar,the influence of concrete strength,longitudinal reinforcement ratio, transverse stirrup and longitudinal steel strength on axially compressive performance was analyzed,the relationship between concrete peak strain,concrete peak stress and concrete strength,longitudinal reinforcement ratio was discussed,the result shows that:①With the increase of concrete strength,longitudinal reinforcement ratio and volume ratio of stirrup hoop,concrete peak strain of axially compressed column is significantly increased,and can be reached above 0.002.Within the longitudinal reinforcement ratio scope commonly used in concrete compression member and stirrup situation ruled by code,the concrete compressive peak strain is at the range of 0.0022 to 0.0026,and the compressive strength of 500MPa grade steel bar can be fully developed.②The specimen bearing capacity was calculated and analyzed in accordance with the formula of axially compressed column in Chinese existing code,the average ratio of test value to calculation value are 1.08（strength of concrete and steel bar is taken as the mean value of test） and 1.24（strength of concrete and steel bar is taken as the characteristic value） respectively,which indicates that calculated formula is in a certain of security.2.According to concrete stress-strain curves of axially compressed column obtained in tests,through the analysis of curve characteristic point and modification of concrete stress-strain curve in Appendix C（Chinese Code）,a concrete stress-strain curve equation in consideration of longitudinal reinforcement and transverse stirrup was derived,of which calculation results are in good agreement with test results,and can be used as reference of nonlinear analysis of concrete structure and members.3.Through test of eccentrically compressed concrete column reinforced with 500 MPa grade steel bar,the influences of eccentricity and longitudinal steel ratio on the specimen lateral deflection,concrete strain at compression edge and longitudinal reinforcement strainwere analyzed,result shows consistent performance with common eccentrically compressed reinforced concrete column.The specimen bearing capacity were calculated according to Chinese existing code,the average ratio of test value to calculated value is 1.18,which indicates that calculated formula is in a certain security.4.On the basis of experimental study of eccentrically compressed concrete column reinforced with 500 MPa grade steel bar,a nonlinear analysis procedure based on Matlab about eccentrically compressed column was worked out,numerical simulation tests of eccentrically compressed concrete column reinforced with 500 MPa and HRB335 grade steel bar respectively were conducted,the impact on second-order effects of eccentricity,slenderness ratio,concrete strength and longitudinal steel ratio were comparatively analyzed,results show that the law of second-order effects of concrete column reinforced with 500 MPa grade steel bar is basically the same with that reinforced with ordinary steel bar.Second-order effects of simulation test specimen were calculated in accordance with Chinese,American and European codes, the calculation results primarily agree with each other,and it can be induced that second-order effects calculation of eccentrically compressed concrete column reinforced with 500 MPa grade steel bar can be designed according to the existing Chinese code provision,and of essentially the same security degree with that reinforced with HRB335 grade steel bar.5.Through the above experiment study and analysis,the design value of compressive strength(f’_y=f_yk/γ_s=500/1.1≈450MPa) and design suggestion for use of 500 MPa grade steel bar in reinforced concrete compression member was proposed,according to above proposal,HRB500 grade steel bar pilot project was designed,a comparative analysis of steel consumption was conducted with that use HRB335 and HRB400 grade steel bar,the results indicate that:①By replacing HRB335 and HRB400 grade steel bar with HRB500 grade steel bar, the reinforcement amount can be reduced under certain conditions,the steel bar crowded phenomenon can be improved in node,beam and column etc.of frame structure,the project quality can be reformed,and better social economy progress can be received.②In order to more effectively promote the use of 500 MPa grade steel in project structure,the calculating method or provisions of crack width and the minimum reinforcement in existing code need to be improved and perfected,and a project basis was provided for 500 MPa grade high strength steel bar in Chinese "concrete structure design code".This article research obtained the State Natural Sciences Foundation（the project authorization number:50578148） and national 863 plans（project number: 2004AA33G050） subsidization.更多还原