The goal of the "Provisions" is to present criteria for the design
and construction of new structures subject to earthquake ground
motions in order to minimize the hazard to life for all structures,
to increase the expected performance of structures having a
substantial public hazard due to occupancy or use as compared to
ordinary structures, and to improve the capability of essential
facilities to function after an earthquake. The "Provisions"
provides the minimum criteria considered prudent for the protection
of life safety in structures subject to earthquakes. The
"Provisions" document has been reviewed extensively and balloted by
the architectural, engineering, and construction communities and,
therefore, it is a proper source for the development of building
codes in areas of seismic exposure. Some design standards go
further than the "Provisions" and attempt to minimize damage as
well as protect building occupants. The "Provisions" document
generally considers property damage as it relates to occupant
safety for ordinary structures. For high occupancy and essential
facilities, damage limitation criteria are more strict in order to
better provide for the safety of occupants and the continued
functioning of the facility. Some structural and nonstructural
damage can be expected as a result of the "design ground motions"
because the "Provisions" allow inelastic energy dissipation in the
structural system. For ground motions in excess of the design
levels, the intent of the Provisions is for the structure to have a
low likelihood of collapse. It must be emphasized that absolute
safety and no damage even in an earthquake event with a reasonable
probability of occurrence cannot be achieved for most structures.
However, a high degree of life safety, albeit with some structural
and nonstructural damage, can be achieved economically in
structures by allowing inelastic energy dissipation in the
structure. The objective of the "Provisions" therefore is to set
forth the minimum requirements to provide reasonable and prudent
life safety. For most structures designed and constructed according
to the "Provisions," it is expected that structural damage from
even a major earthquake would likely be repairable, but the damage
may not be economically repairable. Where damage control is
desired, the design must provide not only sufficient strength to
resist the specified seismic loads but also the proper stiffness to
limit the lateral deflection. Damage to nonstructural elements may
be minimized by proper limitation of deformations; by careful
attention to detail; and by providing proper clearances for
exterior cladding, glazing, partitions, and wall panels. The
nonstructural elements can be separated or floated free and allowed
to move independently of the structure. If these elements are tied
rigidly to the structure, they should be protected from
deformations that can cause cracking; otherwise, one must expect
such damage. It should be recognized, however, that major
earthquake ground motions can cause deformations much larger than
the specified drift limits in the "Provisions." Where prescribed
wind loading governs the stress or drift design, the resisting
system still must conform to the special requirements for
seismic-force-resisting systems. This is required in order to
resist, in a ductile manner, potential seismic loadings in excess
of the prescribed loads. A proper, continuous load path is an
obvious design requirement for equilibrium, but experience has
shown that it often is overlooked and that significant damage and
collapse can result. The basis for this design requirement is
twofold: 1. To ensure that the design has fully identified the
seismic-force-resisting system and its appropriate design level and
2. To ensure that the design basis is fully identified for the
purpose of future modifications or changes in the structure.
General
Is the information for this product incomplete, wrong or inappropriate?
Let us know about it.
Does this product have an incorrect or missing image?
Send us a new image.
Is this product missing categories?
Add more categories.
Review This Product
No reviews yet - be the first to create one!
Welcome to Loot.co.za!
Sign in / Register |Wishlists & Gift Vouchers |Help | Advanced search
