APPLICATION OF THE METHODS OF INITIAL PARAMETERS AND SUBSTITUTE CANTILEVER TO DYNAMIC ANALYSIS OF A MULTI - STOREY STEEL FRAMED BUILDING

Abstract

Although Africa i largely within the earthquake-free zone of the World, recent events have shown that dangerous earth tremors were caused by earthquakes with epicenters at different locations in Africa. In this paper, a dynamic analysis of a 10-Storey building is discussed using a combination of:

1. The static method of P-delta analysis 2. Energy method of determining the minimum Eigenfrequency of the substitute cantiliver and 3. The method of initial parameters.

It discusses the use of structural steel, through the application of deformations obtained from the static method of P-Delta analysis with a virtual force P =1.0 KN varied linearly from the top, to zero at the base as input or initial load. This, combined with the use of energy method for determining the minimum Eigenfrequency of the substitute cantilever and the method of initial parameters was used in a dynamic analysis of a ten-Storey building.

The result of the analysis shows that the maximum deformation (top drift) caused by the siesmic load at the highest point of the building falls within conventionally acceptable limit recommended as a adequate. The minimum total equivalent flexural rigidity, the frequency of oscilliation, period and the frist normal mode of characteristic shape were also deterimined before computing the design of a seismic loading corresponding to the seventh Richter scale.