Seismic analysis of reinforced concrete buildings in the 1931 Hawke's Bay earthquake

Abstract

This thesis examines current earthquake engineering theory and practice regarding Earthquake Risk Buildings to determine if the seismic performance of reinforced concrete buildings is currently underestimated. The types of structural systems investigated are: Reinforced Concrete Structural Walls Unreinforced Brick Masonry (URM) Infill Frames Reinforced Concrete Moment Resisting Frames Buildings with the above systems that survived the February 3 1931 Hawke's Bay earthquake and are still in existence are the set of buildings studied. As much structural information as possible was found for a total of 25 buildings which are analysed in two orthogonal directions. The calculated probable shear and bending strength of each structural member (at ground floor) is compared with the actual estimated seismic shear force and bending moment applied during the earthquake. The restoring moments of structural walls are compared to the calculated overturning moments. The results are expressed as ratios of the above forces and moments of each member. The thesis shows that current theory expects most buildings to fail during both the 1931 Hawke's Bay earthquake and the Code design earthquake but most performed very well with no structural damage. The thesis examines the possible causes of underestimation of seismic performance by current earthquake engineering theory and practice, and makes recommendations for refining and improving practice. Recommendations are also made for further research to establish a simple assessment method for analysing other similar buildings based on the plan area of reinforced concrete structural elements alone.