土木工程外文文献翻译--钢筋混凝土框架异型节点抗震性能试验研究-建筑结构(编辑修改稿)

土木工程外文文献翻译--钢筋混凝土框架异型节点抗震性能试验研究-建筑结构(编辑修改稿)内容摘要：

use of t he hori2 zontal force t ransferred by bigger beam bar . But force is small . 3. 3. 2 load2displacement curves analysis Fig. 9 shows t he typical load2displacement curves at t he beam end of t he exterior and interior joint . The figure showing t hat t he rigidity of t he specimens almo st doesn’ t degenerate when t he initial crack appear s in t he core , and a turning point can be found at t he curve but it isn’ t very obvious. Wit h t he crack developing , an obvious t urning point can be found at t he curve , and at t his time , t he speci2 men yields. Then t he load can increase f urt her , but it can’ t increase too much f rom yielding load to ultimate load. When t he concrete at t he core collap ses and the plastic hinge occured at t he beam end , t he load begins to decrease rat her t han increase. The ductility coefficient of two kinds of joint s is basically more than 3 (except for J 3 9) . But it should be noted t hat the design of specimens is based on the principle of joint core failure. The ratio of reinforcement of beam and column tends to be lower t han practical project s. If t he ratio is larger , t he failure of joint is probably prior to t hat of beam and column , so t he hysteretic curve reflect s t he ductility property of joint core. Joint experiment should be a subst ruct ure test (or a test of posite body of beams and col2 umns) . So t he load2displacement curves at t he beam end should be a general reflection of t he joint be2 havior work as a subst ruct ure. Providing t hat the joint core fails af ter t he yield of beam and column (especially for beam) , t he load2displacement curves at t he beam end is plump , so the principle of “ st rong col umn and weak beam , st ron ger j oi nt should be ensured which conforms to t he seismic re2 sistant principle. The experiment shows t hat t he stiff ness of joint core is large. Before the joint reaches ultimate stage , t he stiff ness of joint core decreases a little and the irrecoverable residual deformation is very small under alternate loading. When joint core enter s failure stage , t he shear deformation increases sharply , and t he stiff ness of joint core decreases obviously , and t he hysteretic curve appears shrink2 age , which is because of t he cohesive slip of beam reinforcement . 3. 4 Influential Factors of Abnormal Joint Shear Capacity The fir st factor is axial pression. Axial pression can enlarge t he pression area of col2 umn , and increase t he concrete pression area of joint core[124 ] . At t he same time , more shears t ransferred f rom beam steel to t he edge of joint core concrete will add to t he diagonal pression bar , which decreases t he edge shear t hat leads to the crack of joint core concrete. So t he existence of axial p ression cont ributes to imp roving t he capacity of initial cracks at joint core. The effect of axial pression on t horough cracking load and ultimate load isn’ t very obvious[1 ] . The reason is t hat cont rasting wit h no axial pression , the accumulated damage effect of joint core under rever sed loading wit h axial pression is larger . Alt hough axial pression can improve t he shear st rengt h of concrete , it increases accumulated damage effect which leads to a decrease of the ad2 vantage of axial pression. Therefore t he effect of axial pression on t horough cracking load and ultimate load is not very obvious. Hence , considering the lack of test data of abnormal joint , t he shear capacity formula of abnormal joint adopt 0. 05 nf c bj h j to calculate the effect of axial pression , which is based on the result s of t his experiment and referenced to t he experimental st udy and statistical analysis of Meinheit and J irsa , et [5 ] . The second factor is horizontal stirrup . Horizontal stirrup has no effect on t he initial cracking shear of abnormal joint , while greatly improves t he t horough cracking shear . Af ter crack appeared , t he stirrup begins to resist t he shear and confines t he expansion of concrete[ 6 ] . This experiment shows t hat t he st ress of stirrup s in each layer is not equal . When the joint fail s , t he stirrup s don’ t yield simultaneous. Fig. 10 shows t he change of st ress dist ribution of stirrup s along core height wit h t he load increasing. Through analyzing test result s , it can be known t hat 80 percent of the height at the joint core can yield. The last factor is the change of sec2 tion size of t he beam and column. The section change decreases t he initial crack2 ing load about 30 p resent of abnormal joint and makes t he initial crack appear at t he position of joint mi nor core. The rea2 son for t his p henomenon is t hat small up2 per column section makes t he confinement of mi nor core concrete decrease and t he edge shear increase. But t he section change has lit tle effect on thorough cracking load. Af ter t horough cracking , the joint enter s ultimate state while the external load can’ t increase too much , which is dif2 ferent f rom t he behavior of abnormal joint t hat can carry much shear af ter thorough cracking. 3. 5 Shear force formula of abnormal joint As a part of f rame , t he design of joint shall meet t he requirement s of the f rame st ruct ure design , namely , t he joint design should not damage t he basic performance of t he st ruct ure. According to the principle of st ronger j oi nt , it is necessary for joint to have some safety reserva2 tion. The raised cost for conservational estimation of t he joint bearing capacity is small . But t he con2 servational estimation is very important to t he safety of the f rame st ruct ure. At t horough cracking stage , t he。