The choice of the basic plan shape and configuration of a superstructure to
withstand earthquake ground shaking is the most critical. Building structures
have several types and configurations but here is no universal ideal
configuration for any particular type of building. However, the following
guiding principles will help the designer in selecting an adequate building
configuration, structural layout, structural system, structural material and the
- The superstructure and non-structural components of building should be light
and avoid unnecessary masses. Smaller masses will have smaller earthquake forces
- The building and its structures should be simple, symmetric and regular in
plan and elevation to prevent significant torsional forces, avoiding large
height-width ratio and large plan area.
- Superstructure should have relatively shorter spans than non-seismic structure
and avoid use of long cantilevers.
- The non-structural should either be well separated so that they will not
interact with the rest of the structure, or they should be integrated with the
structure. On the latter case, it is desirable that the structure should have
sufficient lateral stiffness to avoid significant damage under minor and
moderate earthquake shaking and toughness with stable hysteric behavior (that
is, stability of strength, stiffness and deformability) under the repeated
reversal of deformations which could be induced by severe earthquake ground
motion. The stiffer the structure, the less sensitive it will be to the effects
of the interacting non-structural components, and the tougher is, the less
sensitive it will be to effect of sudden failure of the interacting
- Some building components (architectural, mechanical and electrical) can become
very responsive during the earthquake shaking of the building foundation. The
effects of the interaction can be grouped into two categories; first the effect
of the response of the structural system on the non-structural components; and
second the effect of the non-structural components on the response of the
structural system. The more flexible the basic structural system the worse the
effects of the non-structural components will be.
- Superstructure should be detailed so that the inelastic deformations can be
constrained (controlled) to develop in desired regions and according to a
- Superstructure should have the largest possible number of defense lines. It
should be composed of different tough structural subsystems which interact or
are interconnected by very tough structural elements (structural fuses) whose
inelastic behavior would permit the whole structure to find its way out from
critical stage of dynamic response.
- A structure should have the largest possible number of internal and external
redundancies. Further, it should have sufficient ductility, toughness and stable
hysteric behavior under repeated cycles of deformation reversals. To achieve
this it is necessary to proportion (size) and detail its members, connections
and supports so that all the inelastic deformations are constrained (controlled)
to develop in desired regions and according to a desirable hierarchy, and are
dispersed in a sufficiently large number of regions over the plan and height of
the whole structure.
- Superstructure should be provided with balanced stiffness and strength between
its members, connections and supports. Collapse and severe damage of buildings
due to lack of good connections is common.
- The stiffness and strength of the entire building should be compatible with
the stiffness and strength of the soil foundation.