Study On Seismic Analysis And Conceptual Design Of RC Mega-frame Structure

The reinforced concrete (RC) mega-frame structure, an important branch of thehigh-rise building mega structure system, has good beneficial results. The RCmega-frame structure has a bright prospect, it not only can ensure the overall stabilityand lateral stiffness of the structure, but also effectively reduce the cost of theconstruction and reasonably solve the contradiction between architectural function andstructural layout requirements. However, there is no earthquake damage expericenceavailable for reference because that the RC mega-frame structure has not sufferredstrong earthquakes.Additionally, prototype and model tests of RC mega-frame structureare very complex because of the vast amount of structural parts, and no detailedinstructions in the current code.Therefore, it is theoretically and practically meaningfulto study the seismic conceptual design of RC mega-frame structure.By use of large-scale finite element analysis and design program SAP2000V14.1,two RC mega-frame structure models with solid web beams and truss beamsrespectively are established in this paper. In order to study the seismic performance ofRC mega-frame structure in depth, modal analysis, response spectrum analysis andelastic-plastic static Pushover analysis on models are conducted.As the consequence shows, RC mega-frame structure has a good integrity, and itsdeformation depends on the first several vibration modes.The elastic and elastic-plasticlateral displacement curves of RC mega-frame structure are of bending-shear type, andthe inter-storey drift curves of each huge storey are parabolic.With the equalconsumption of materials, the lateral stiffness of RC mega-frame structure with trussbeams is greater than that with solid web beams, however the latter is greater than theformer in terms of ductility.The dynamic characteristics of RC mega-frame withinverted V-shaped braces is close to that with X-shaped braces,and the lateral stiffnessof them are greater than that with-shaped braces. According to the mechanicalcharacteristics and advantages of RC mega-frame structure, combined with the resultsof response spectrum analysis and elastic-plastic static Pushover analysis,recommendations on seismic conceptual design of RC mega-frame structure areproposed as follows:(1) to improve the relative stiffness of the secondary frameappropriately;(2) to follow the principle “strong column and weak beam” in primaryand secondary frames respectively;(3) to emphasize improving load capacity in primaryframes and ductility in secondary frames;(4) to strengthen the weak layer and the weakparts.