UNINTENDED CONSEQUENCES OF CODE MODIFICATION

The code provisions for earthquake resistant design have been substantially
revised in the conversion of the 1994 Uniform Building Code (UBC) through the
1997 UBC to the 2000 International Building Code (IBC). This paper examines
five of the most recent changes to the code: the vertical earthquake component;
the seismic design of nonstructural components and equipment; the maximum
inelastic response displacement; the use of 2/3 of the maximum considered
earthquake; and the reliability/redundancy factor. The apparent reasoning behind
these five changes and some of the unintended consequences are discussed