Performance based design of Different structural systems in High rise structures

Abstract

The growing developments all over the world, rapidly increasing urban population, need of smart cities and the desire to maximize rentable space has presented the need to build higher and higher. Skyscrapers are becoming an integral part of any country's global economy. Although the feasibility of tall buildings has always been a function of the resources and the technology, advancements in structural engineering and construction technology have greatly pushed the height barrier. As the height of the building increases, the lateral loads become more critical than the gravity loads, thus the conventional rigid frame structures which are used for low rise to medium rise buildings cannot be used in high rise buildings. There is a need to explore new structural systems for high rise buildings. Out of the various structural systems Wall frame structure, Framed Tube Structure, Core with Outrigger and belt, Diagrid structures and High Efficiency structure are widely used in high rise structure because of their better lateral load resistance. Wall Frame structure resist lateral loads due to the interaction of central core and frame due to their different modes of bending. Framed Tube structure acts like a perforated cantilever tube, but has a disadvantage of shear lag. Outriggers provided at mechanical levels helps reduce the shear lag effect and impart additional lateral stiffness due to the lever arm action. Diagrids on the other hand are free of vertical column and resist all the lateral and gravity force by their axial action. High efficiency structure is based on the idea that maximum gravity loads must be transferred to the perimeter columns to resist overturning moments and connect these perimeter columns to shear resisting system to resist lateral load. The aim of the present study is to carry out analysis and design of five different structural systems used in high rise buildings considering the secondary effects and effects of sequential loading. The structural systems are compared on the basis of strength and servicibility criteria, to find out the most efficient structural system. For this, a cruciform shaped 110 storey building with plan dimension as 48m 48m, along with a core of 20m 20m is designed for five aforementioned systems using MIDAS Gen software. A comparison based on member sizes, building drift, time periods, material consumption and an efficiency factor has been carried out to deduce the most efficient structural system. A new parameter called the efficiency factor that is a measure of buildings stiffness to normalized cost is derived to find out the most effecient structural system. From the above study it is found that high effeciency structure is the most effecient whereas Wall frame structure is found to be least effecient, for 110 storey buildings considered in this study Performance based design of prevalent structural systems used in high rise buildings has also been carried out in this study. Wind data records of a typhoon have been presented and a time history function has been generated to carry out non linear dynamic analysis of the structure. High Effeciency structure has been found to be most efficient in terms of building performance based on interstorey drift ratios, plastic rotation in beams & Human comfort performance criteria, whereas Wall frame structure have been the least efficient among structural systems considered in this study. Performance parameter that is a measure of structure's resilience to normalized cost is derived to find out the most efficient structural system in terms of building's inelastic performance.