Page 133 - Bridge and Highway Structure Rehabilitation and Repair

108 SECTION 1 ADMINISTRATIVE ISSUES

Table 3.11 History of bridge failures due to earthquake (design issues).
U.S. Bridges Location Year Details of Failure
I-S and Antelope Valley Freeway Near San Fernando, CA 1971 Natural hazard (Sylmar Earthquake)
interchange
Cypress Freeway Oakland,, California 1989 Natural hazard (Loma Prieta Earthquake)
Section of east span of San San Francisco, California, 1989 Natural hazard (Loma Prieta Earthquake)
Francisco-Oakland Bay Bridge
Motorway bridge Junction Antelope Valley 1992 One span collapses during earthquake
Interstate 5 Bridge Los Angeles, California 1994 Earthquake measuring 6.6 on the Richter scale

Japanese Bridges
Showa Bridge Showa 1964 Intensity 7.5 Niigata
Earthquake, movement of the pier foundations
natural hazard (earthquake)
Nishinomiya Bridge Nishinomiya 1995 Hyogo-Ken Nanbu Earthquake, separation of the
two supporting piers caused by the lateral ground
displacements
Hanshin elevated expressway Hanshi 1995 Hanshin Earthquake (7.2 on Richter Scale), fi ve
(Kobe-Osaka highway) sections of expressway were tossed aside
Bridge in Kashiwazaki City Niigata 2007 Due to Niigata-Chuetsu-Oki Earthquake

Pakistani Bridges
Various bridges North of Pakistan and 2005 Intensity 7.6 Pakistan Earthquake
Azad Kashmir

3.14.9 Suggested Preventive Action against Earthquake Failures
1. Some seismic retrofits include the use of isolation bearings, snubbers, and restrainers at

discontinuous beams over piers; seismic detailing; the provision of ductile joints; and the
adoption of seismic criteria in design. Member sizes and joints must be designed for the

AASHTO LRFD load combination strength VI. Details of seismic retrofits are given in
Chapter 10.
2. Earthquake engineering should consider the vulnerability of column failure and incorporate
design against progressive collapse. The need for ductile detailing to prevent column damage
has been emphasized in NCHRP 12-49. In design, ductility needs to be linked to specifi c
collapse mechanisms and any cantilever action resulting from loss of support. A progressive
collapse approach may increase bridge safety.
3. Conclusions for seismic behavior: It has been shown that ground response during earthquake
depends upon the soil conditions underlying a site. A gross instability of the soil may develop,
resulting in large permanent movements of the ground surface and associated distortion of
supported structures.
The intensity of the earthquake movements should be studied in the forms of displacements
and accelerations, as useful to the seismic engineering profession. Therefore, it is important to
record destructive earthquakes by means of accelerograph. From the recorded accelerations the
response spectra for different location areas may be calculated and the results may be applied
in the seismic design of foundations and structural engineering.