| Beam-column joint is the key component which links beam and column. Under sesmic actions, joint core zone is in shear-compression composite stress state which is caused by tension on one diagonal direction and compression on other diagonal direction of joint core zone, so shear failure occurred in joint core zone, and energy-dissipation capacity is rather low. The design principle of strong joint based on Code in China must be met for design of frame structures, which leads to reinforcement congest, construction difficulty and imperfect casting. In order to improve seismic performance and reduce construction inconvenience, the seismic performance experiment study on new-style beam-column joint, for which fiber-reinforcent concrete(FRC) was used in joint core zone, beam end and column end next to joint core zone,was completed. Meanwhile, calculation model of shear bearing capacity and shear stress-shear strain of joint core zone and calculation model of interstory shear-deformation of FRC beam-column subssublages was also put out. Finally,performance-based seismic design method study was completed on frame structure with FRC used in partial section. So the main contents and results are as follows:(1) The quasi-static experiments on seven FRC specimens and one RC specimen as contrast specimen were carried out, and the failure process, failure modes,load-carrying capacity, deformation capacity, energy dissipation capacity, the plastic hinge rotation capacity of beam end, the shear deformation capacity of joint core zone and deformation capacity of column end was also analyzed. The results indicates that the increase of axial load ratios in the range of test axial load ratios can improve the shear capacity of joint core zone, the use of FRC in joint core zone can substitute shear-sturrups partly, increase of FRC length of both beam end and column end can improve energy-dissapation capacity, and FRC beam-column subsseblages has already excellent energy dissipation capacity and deformation capacity before diagonal cracks formed.(2) By analyzing shear bearing mechanism, the diagonal strut mechanism and the truss mechanism would be existed in joint core zone. By analyzing the proportion of shear capacity undertaked by the diagonal strut mechanism and the truss mechanism to the total shear capacity, the calculation model of shear bearing capacity of joint core zone, considering FRC strain-hardening characters, was put out. According to longitudinal stress when shear capacity of joint core zone arrived to maximum value,the failure modes of beam-column joint can be judged. Then, according to proportion of shear capacity undertaked by the diagonal strut mechanism and the truss mechanism to total shear mechanism when shear capacity of joint core zone arrived to maximum value,the calculation model of shear bearing capacity of joint core zone can be simplized into single restraint diagonal strut mechanism. Finally, the rationality of both the calculation model and simplified calculation model of shear bearing capacity of joint core zone was verified by test dates.(3) According to equilibrium equitions, coordination equitions and constitutive relationships, the calculation model of shear stress-shear deformation of joint core zone which was programed by using MATLAB software was put out. At the same time, the calculation method of shear stress and shear strain of crack point, yield point and peak point was also put out, and the rationality of calculation model was verified by test dates.(4) According to deformantion relationships between total deformantion of beam-column subssemblages and shear distortion of joint core zone, beam deformantion as well as column deformantion, and the shear capacity relationships between joint core zone and column end, the interstory shear-deformantion relationship calculation model was put out. Also, the proportion of interstory deformantion caused by shear distortion of joint core zone, beam deformation, and column deformation to the total interstory deformantion was analyzed. The result indicates that interstory deformantion caused by shear distortion of joint core zone in which shear failure occurred can be not ignored.(5) Firstly, according to lateral drift curves under different performance levels of FRC frame structures, the responding lateral drift modes by fitting lateral drift dates were achieved. Secondly, according to seismic performance targets and lateral drift curves under different performance levels, the base shear capacity of FRC frame structure under frequent earthquakes, fortification intensity earthquakes and severe earthquakes was calculated. Thirdly, design of beam and column section was completed according to design value of section internal force by combining designed seismic effect and corresponding gravity load effect. Finally, the pushover analysis and the dynamic time-history analysis on designed FRC frame structure and RC frame structure was completed to compare advantages and disadvantages of the seismic performance, and the feasibility of performance-based design method was also verified.(6) Both maximum interstory drift ratios and roof drift ratios were choosed as Engineering Demand Parameter respectively, and the seismic fragility analysis on performance-based designed FRC frame structure and corrensponding RC frame structure was completed. The result indicates that maximum interstory drift ratio as Engineering Demand Parameter is more reasonable than roof drift ratio firstly. Secondly,seismic performance of FRC frame structure is better than that of RC frame structure by comparing the median values of collapse capacity. Thirdly, according to the transcendental probability under different performance levels, the rationality and reliability of performance-based designed FRC frame structure and corresponding RC frame structure, as well as the feasibility of FRC as a substitude of normal concrete was also verified furtherly. |
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