Foundation–structure systems over a rupturing normal fault: Part I. Observations after the Kocaeli 1999 earthquake

Abstract

Triggered by reactivation of the strike-slip North Anatolian Fault, the disastrous M w 7.4 Kocaeli (Turkey) earthquake also produced normal faulting in the pull-apart basin of Gölcük. Surface scarps from such faulting reached almost 2.5 m in height. Several structures were crossed by the surface rupture. As expected, many of them either collapsed or were severely damaged. But, surprisingly, several structures survived the outcropping dislocation essentially unscathed. In fact, in some cases the surface rupture path seemed to have deviated, as if to "avoid" rupturing directly underneath a structure. In other cases damage was substantial even though the fault rupture was "masked" by the near-surface soil and did not create a scarp. The rigidity and continuity of the foundation appears to have been one of the crucial factors affecting structural performance. Interestingly, the examined structures were supported on a variety of foundation types, ranging from isolated footings, to rigid box-type foundations, to piled foundations. The paper outlines a reconnaissance of the area, providing a documented description of the observed interplay between the rupturing fault, the soil, and the structure, along with the results of soil exploration and geological trenching. In the companion paper, Part II, each system is analysed numerically to confirm the conclusions of the present paper, reveal the main aspects of Fault Rupture-Soil-Foundation-Structure Interaction (FR-SFSI), and help develop deeper insights into the mechanics of successful performance of structures built on top of such faults.

Centrifuge modelling of normal fault–foundation interaction

“…This agrees with observations from field case histories (e.g. Anastasopoulos and Gazetas 2007a;Faccioli et al 2008) where heavy buildings appeared to deviate the fault displacements without significant damage.…”

“…A 60 • dip angle was selected to agree with common field conditions, and the soil response was modelled to be drained and quasi-static agreeing with findings from case histories Anastasopoulos and Gazetas 2007a).…”

A simplified Nonlinear Sway-Rocking model for evaluation of seismic response of structures on shallow foundations

“…This phenomenon, induced by either heavy structural loads that are unevenly distributed across the footing, poor soil conditions, or the combination of both, can lead to failure of structural components and hence, non-repairable damage or collapse of structures [7]. Mat (or Raft) foundations, in these cases, are more suitable to spread the loads from the structure to the ground.…”

Bridge–Pier Caisson foundations subjected to normal and thrust faulting: physical experiments versus numerical analysis

“…Structures straddling the fault are threatened by structural damage (the extreme being collapse) and excessive movements (most significant: uncontrollable rotation). Such effects on structures have been numerous and conspicuous in the earthquakes of Nicaragua 1972, Kocaeli 1999, Düzce 1999, Chi-Chi 1999, Wenchuan 2008 [1][2][3][4][5][6][7][8][9][10].…”