Analysis and Design of Pyramidal Roof Slab

Abstract

Many historical buildings/monuments have been built having shape of a pyramid. The mystery and attractiveness of pyramidal shape have made pyramidal building undergo a renaissance in today’s architectural design. Pyramidal roof slab is not a common structure because of its typical formwork and expensiveness. In countries where there is heavy snowfall, pyramidal slab is adopted so that snow can slide easily due to its sloping pattern. But in India it is constructed rarely due to less snow fall, typical form work, requirement of skilled labor and its expensiveness.

A roof/slab consisting of a plane surface triangular in shape and bounded on each side by a sloping ridge forming the intersection of adjacent planes and culminating in a common vertex is known as pyramidal roof. Triangular panels of pyramidal slabs make an angle with vertical axis. According to that angle effect of thrusts and moments is decided. There are two types of moments: i) Along the slope ii) Across the slope depending upon the boundary conditions.

The primary aim of the work is to analyze and design the Pyramidal roof slab. Different boundary conditions are considered like Pyramidal panels (a) with and without ridge beam (b) with and without edge beam (c) supported on wall and (d) supported on columns with different conditions. Primary thrust, Secondary thrust, Moments in different direction as well as at the edges and ridges are determined. As per that Design is carried out using Limit State Method.

Analysis is also checked using SAP-2000(v 9.1). Behavior of slab, beam and column is critically studied by changing meshing till the required precision of output is achieved. Variation in forces and moments with change in height, thickness, base angle and base dimension are presented graphically. Detailing of various elements like slab, edge beam, ridge beam, and column is also shown. Visual Basic is used as a programming language because it is user friendly and easy to make modules compared to C++ programming.