STUDY OF BUILDING WITH VERTICAL POST TENSIONED COLUMNS UNDER EARTHQUAKE LOAD BY PUSHOVER ANALYSIS

Abstract

Vertical post tensioned columns are widely used for bridges in the USA and other countries. These columns can give higher recentering ability and uncracked section after earthquake vibration effects. This method is applied to general building columns. In current stud, their earthquake behavior is evaluated by doing pushover analysis. In this analysis, performance parameters of building and modified response reduction factor are evaluated. Vertical bonded tendons are equally distributed along four sides of the columns. The amounts of PT (pre-stressed) steel provided are 0.4%, 0.8%, 1.2% and 1.6% of the column cross section area. RC (reinforced concrete) space frame building with aspect ratio 4 is selected for study. Only corner columns are pre-stressed. The results of the analysis show that increases in Performance point, maximum base shear (V max) and response reduction factor (R) can be achieved by increasing PT steel and PT force in tendons. Number of Hinges develop in frame will decrease in initial cases and increase in later part as increase in PT forces. Here columns are punished by giving extra vertical PT force up to 50% of its axial load capacity with maximum reinforcement steel up to 4% of the area.