The Performance-based Seismic Design Of Tall Building Structures Beyond The Code-specification

With the development of global economy integration and technology revolution, moremodern buildings have emerged to be high-rise structure, multiple functions, complexconstruction, which requires the civil engineer focusing on the collapse causing by earthquakeand new effective analyzing methods. Besides, economic losses and people’s safety should beestimated and balanced through the whole design and analyzing progress. Therefore, theguiding ideology high-rise building has been adjusted from the traditional three-level offortification and two-stage of seismic design to the performance-based seismic designgradually.Base on the long-term study, the topic of this thesis is to indicate the background of theperformance-based seismic design theory and its application in civil realm, to indicate theimportance and requirement by applying the seismic ideology into the process of architecturedesign, as well as to analyze the difference between the traditional methods and theperformance-based seismic method. In addition, certain project is used to demonstrate all theaspects as mentioned above, and the major aspects are showing as fallowed:1. Regarding to the phenomenon and damage of the earthquake, as well as the flaws andlimits in earthquake data collection and seismic design process, it is necessary to develop theseismic design in civil realm, which involves some new basic models of seismic design byconcluding the pervious theory and analysis experience, to satisfy the functional requirementsand the usage in different areas all over the world.2. By analyzing and design certain real high-rise project, it is possible to find out itsconstruction type and over-limit issues through the national standard, which helps to set upthe seismic design phases and target. In the analyzing process, the structure is modeling bythree different softwares, PKPM SATWE, PMSAP and GSSAP, to analyze the damage of theearthquake in three phases, the mild earthquake, the mid-level earthquake and the rareearthquake.Moreover, elastic modeling analysis is applied and the results is compared with thenational standard requirements in the three phases separately. Firstly, in the mid-levelearthquake analysis, shear wall and the column are still within the elastic stage, but allowsome subordinate part into the plastic stage. Secondly, Flexible floor analysis is required inthe mid-level earthquake, which is to improve the floor that could provide transmit path to thehorizontal force reliably and effectively. Thirdly, using PUSH&EPDA software applies to pushover analysis the structure in the rare earthquake circumstance, and the data shows themaximum inter story elastic-plastic displacement angle is smaller than the shear wall elasticdrift angle by considering the P-Δ affection.3. The results from the analysis above should be compared with the national standard incertain indicators to meet the lowest requirements, which are the periodicity, displacement,the ratio of rigidity and weight, the ratio of shear and weight, structure irregular torque degree,irregular floor, dimensions mutation, portion wear layer columns, towers bias ect. Byselecting the dynamic behaviors target, certain actions are made to strengthen the structure,especially the related weak components according to the results of elastic modeling analysisand dynamic response analysis of the three phases separately. And the strength actions includeas followed:First of all, for the situation of irregular torque structure which causes the major damage,action should be made to strength the flexible function of the building for brittle failure.Normally, lowering the ratio of triaxial stress, the shear stress and increasing the percentage ofthe steel usage in the critical components will help.Secondly, to make sure the floor could provide transmit path to the horizontal forcereliably, it is necessary to strength the part with holes, floor discontinuous and over-bearingparts by using two layers two damnations steel frame, and thicken the floor will help.Thirdly, using sections to the shear wall to increase the percentage of the steel usagecould make the shear wall stand in a higher degree of moment and bigger push-over force.Fourthly, while using1.5%of steel volume in column’s single edge and0.8%for shearwall to experience the Push-over analysis, if the result shows all the major parts are under thelowest limit of performance-based seismic design target, it indicates that structure is stable inthe rare earthquake.To sum up, By studying the theory of seismic design and applying it to the real project, itindicates its flexibility and feasibility in the civil realm. If the structure only depends on thenational standards for strengthen the whole structure by increase the usage of steel even forthe unnecessary components, it is hard to satisfy the economic indicators. Moreover,performance-based seismic design suits the modern building showing autonomy, as well aspromising the flexibility and verification for architect’s imagination. In the same time, thestructure could be more fit in usage functions, especially some particularly requirements andsafety with a lower building budget, of which the standard design process could not guarantee.In additional, performance-based seismic design requires a higher professional level of theengineer, which is good for skill promotion.