Parameter Optimization Of R.C.Frame Seismic Design Based On Failure Loss Expectation

On the instruction of the performance-based seismic design method and the soft engineering design theory, a optimization model for structures based on a failure loss expectation is presented on this dissertation. By investigating the failure models and damage degree of frame structure systems under the action of earthquake, taking the lowest expenditure of the structure in its whole designed service life as a objective function, the research of several parameters in frame structure seismic design is carried through. The works that have been done involve following aspects:(1) Merits and faults between general optimization model and reliability-based optimization model for structures are discussed, and according the important engineering fact that different failure modes of structure systems have different consequences and the structural damage degrees are varied under earthquakes with different intensities, as well as economic loss, a optimization model for structures based on a failure loss expectation is presented.(2) The specifications in different country codes about "strong column-weak beam" which is a seismic conceptual design are compared. Utilizing the improved branch and bound program by Matlab, the main failure modes and its failure probabilities of RC frames under the action of frequent earthquake are identified. Through forecasting the structural losing cases while different failure mechanisms are formed under the seismic action, rational target reliability of "strong column-weak beam" is investigated, and combining a concrete calculate example, the moment magnification factor of RC frame column in seismic design is optimized.(3) Beams and columns are tandem system make up of shear failure and flexible failure. The former is brittle failure and the latter is ductile failure, and the loss value of brittle failure is further greater than that of ductile failure. Based the former fact, the shear magnification factor of RC member in "strong shear-weak moment" design is optimized utilizing Monte Carlo random simulation program by Matlab, and a more appropriated value for code is suggested. During analyzing, the statistic parameters of initial eccentricity e₀ are outlined discussed.(4) Based on the analysis method of RC structural damage indexes under the seismic action and the investigated seismic data of destroyed buildings, the quantified relation between the damage indexes and losing value of structures is serialized, which can be utilized to forecast the earthquake consequence of designed structure...