Seismic behaviour of Micropiles




2.1 INTRODUCTION

The response of a structure subjected to seismic or dynamic loading primarily

depends on the characteristic of the site response, the external loading, the mechanical

properties of the surrounding soils, and the structure itself. An extensive literature review

was conducted on site response and soil-structure interaction problems. Before dwelling

on these problems, post earthquake observations were reviewed. Past earthquakes have

indicated contradictory observations of the influence of battered piles on the response of

a structure.



2.2 POST EARTHQUAKE OBSERVATIONS

Post earthquake observations provide an excellent indication of pile performance

under earthquake loading. Different degrees of structural damage have been observed

relating to different types and inclinations of piles supporting the structure. The following

paragraphs present several post earthquake observations.

The October 17, 1989 Loma Prieta earthquake (moment magnitude, M

yielded important observations on pile performance. SEAOC (1991) reports that the 7th

Street Terminal Complex suffered extensive damage as the 16 in. square pre-stressed

concrete battered piles supporting the Public Container Wharf failed in tension at their

connection to the deck. Similar damage was observed at the Matson Terminal Wharf on 7

Street with additional damage to the back row of the vertical piles. Failure of the 16 in.

square pre-stressed concrete battered piles at or near the pile cap connection was noticed

w , of 7.1)


Download
*