High-rise Structural Systems in Steel

Abstract

The design of high rise buildings is governed by lateral loads caused by wind or earthquake. In tall structure stiffness is generally more important than its strength. It is very important to ensure the adequate stiffness of structure against the lateral loading caused by the wind or earthquake. Lateral load increases rapidly with increase in structure’s height. Under wind loading the overturning moment at the base of a building is proportional to the square of the height of building and deflection is proportional to the fourth power of the building height. Different structural systems are suitable for high-rise building to satisfy the design requirements. But it is important that the selected structural system should be such that the structural members can be utilized to its full design capacity. The objective of the present study is to understand the behavior of the structural systems of high-rise building and to design structural systems including effects of the along wind and across wind. In this report evolution of the structural systems in steel is discussed. The case studies on Steel-plate shear wall, Outrigger and Diagrid system are presented. The behavior of the Moment Resisting Frame, Braced frame, Outrigger, Diagrid and Seel-plate shear wall frame are discussed. The analysis and design of 50 storey Moment resisting steel frame is carried out. The Dynamic along wind load is calculated by IS: 875(III)-1987 and by IS:875-Draft code. The dynamic across wind load is also calculated by equivalent static wind load method. The along and across wind both are considered simultaneously for analysis and design. The design of members are carried out as per IS: 800-2007. The parametric study is carried out by changing the periphery and core column sizes to satisfy the stiffness requirement. The effect of sequential loading in analysis of structure is studied by considering the single storey construction sequence. The results of sequential analysis in terms of axial force and bending moment at the base of column for self weight case are presented. The analysis and design of 50 storey Steel plate shear-wall (SPSW) structure is presented. The unstiffened steel plate wall panel is taken for study. The design of SPSW including preliminary design and final design is presented. The effect of the different boundary element sizes on the web plate tension stress and on the angle of tension stress is studied. vi Approximate analysis of outrigger structural system is carried out by converting three dimensional structure into two dimensional structure. The optimum location of one outrigger and two outrigger system subjected to uniform lateral loading is presented. The analysis and design of 50 storey building with one outrigger at mid height is carried out. The comparisons of the Moment resisting frame, Steel plate shear-wall frame and Outrigger systems in terms of building response like time period, top storey displacement, drift and design forces are carried out. The Shear-Wall frame system requires 8% less steel and Outrigger system requires 10% less steel compared to Moment resisting frame, for 50 storey building considered in this study. The major project is divided into various chapters. Chapter 1 includes the evolution of structural systems, case studies of tall structure, objective of work and scope of work. The literature review about the structural systems, Steel-plate shear wall, Outrigger system, Diagrid and wind loading is presented in chapter 2. The behavior of Moment resisting frame, Braced frame, Outrigger, Diagrid and Steel-plate shear wall is discussed in chapter 3. Analysis and Design of 50 storey Moment resisting frame is presented in chapter 4. Analysis and Design of 50 storey Shear-wall frame is discussed in chapter 5. Optimum location of outrigger under uniform lateral loading and Design of 50 storey Outrigger structure are included in chapter 6. The comparison of Moment Resisting Frame, Shear-Wall Frame and Outrigger structure in terms of time period, top storey displacement, drift and total quantity of steel required is presented in chapter 7. Summary, conclusions and future scope of work are included in chapter 8.