Civil Engineering Reference
In-Depth Information
Figure B.37
Excessive lateral displacement during the 1995 Kobe, Japan, (
left
) and the 1999 Chi-Chi, Taiwan,
earthquake (
right
) (
after
FEMA, 2000 )
the left-hand side) and the pounding that may occur between adjacent structures. Hammering between
buildings employing different materials of constructions, e.g. RC or masonry and steel, is likely to
occur because of the difference in relative stiffness of structural systems.
In several cases, damage was found in frames employing different structural materials along the
height of the building. This construction technique is very common for high- rise buildings, especially
in Japan (Aoyama, 2001). High-strength columns are utilized at the lower storeys, while intermediate
and upper fl oors employ steel members. Abrupt variations of stiffness along the height of structures
generate stress concentrations and high inelastic demands, for example, at the connection between steel
and RC elements. Lack of maintenance, e.g. evident material corrosion, and inadequate lateral resisting
systems caused several partial or total collapses of steel frames in the Kobe region.
B.3 Examples of Damage to Bridges
An effi cient transportation system plays a vital role in the development of a modern society, mainly
due to the inter-reliance of various industries and the increased trend for outsourcing. Modern trans-
portation networks are referred to as lifelines, the integrity of which has to be protected alongside water,
electricity and gas networks. While roads are an important component of transportation networks,
bridges are strategic and more sensitive to damage from natural disasters.
Typical earthquake -induced structural failures of bridges are discussed in Section 1.4.1. For RC
bridges, observed weaknesses can be summarized as follows:
(i)
Abutment backfi ll settlement and erosion;
(ii)
Flexural failures in plastic hinges with inadequate confi nement;
(iii)
Shear failures in short single columns, piers, multi-column bents, columns with fl ares and other
accidental restraints, and columns in skewed bridges;
(iv)
Inappropriate location of lap splices in pier members, causing shear failure;
(v)
Compressive failures of columns and piers with corresponding rebar buckling and stirrup
openings and ruptures;
