Civil Engineering Reference
In-Depth Information
Mass
Figure A.10
Irregularities in elevation due to non-uniform stiffness, strength and mass distribution
Key:
Circles indicate areas of concern
without interruption from their foundations to the top of the building. This ensures a clear and
continuous load path and prevents concentrations of high ductility demands.
Vertical and plan layouts should be selected such that damage of adjacent structures is avoided.
Excessive drifts during earthquakes may cause damage to proximate systems or between different wings
of the same structure (also referred to as 'pounding'). Structural damage for pounding (also termed
' hammering ' or 'battering') is induced by high momentum transferred between colliding structures.
Pounding is a major cause of damage to buildings in cities located in seismic regions. It may occur in
multi-mass structures, which employ structural components with very different relative stiffness.
Typical examples are buildings with RC infi lled frames for lower storeys and steel bare frames for the
upper storeys. In this case, the less stiff structural systems and attachments (penthouses, roof tanks)
move considerably with respect to rigid parts; high differential movements may cause pounding. Bell
towers in historical buildings typically suffer damage caused by this type of pounding. Out- of - phase
vibrations and separation joints inadequate to accommodate large drifts have caused extensive damage
worldwide in past earthquakes (e.g. Kasai
et al
., 1996). Examples of effects of pounding in building
structures are shown in Figures B.17 and B.18. Pounding may also cause damage in multiple- frame
