< Structural & Civil Engineering · Inspections, Earthquake / Seismic, Retaining Wall Design

Earthquake / Seismic Analysis

for residential homes, commercial buildings, bridges and retaining walls . . .

Earthquake or better known as seismic analysis and design is based on procedures prescribed by applicable building codes. Depending if it is a building or a public facility structure such as bridge or a retaining wall, different codes will apply. Building codes for new or remodel building construction is based on the International Building Code and/or the International Residential Code. Assessments of existing and older buildings are typically prescribed by the ASCE/SEI 31-03, Seismic Evaluation of Existing Buildings. Structures related to infrastructure design, such bridges and retaining walls are generally prescribed by the AASTHO LRFD Bridge Design Specification. Specific requirements are typically dictated by the local jurisdiction.

The seismic analysis will evaluate the complete lateral and vertical force-resisting systems within the structure that are capable of providing adequate strength, stiffness, and energy dissipation capacity to withstand the design ground motions based on deformation limits and strength demand. The motions occur along the horizontal directions of a building structure. The structure is modeled to determine the effects that will be used for the design. The design seismic forces are looked at along the height of the structure. There are various procedures prescribed by the code that will allow the engineer to select the level of detail that is appropriate for the specific structure.

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Residential Homes

Our staff can efficiently engineer your residence to resist seismic loads from an earthquake. We can provide proper lateral resistance for the typical wood-framed home with shear walls and diaphragms. The incorporation of other conventional building materials such as concrete, masonry, and pre-engineered building products can also be considered. We can also provide practical solutions for strengthening and repair with proven renovation details. If steel framing is required, we can evaluate the need for a moment frame. We provide economical and conventional construction provisions that meet the required codes including the International Building Code (IBC), International Residential Code (IRC), ASCE 7-10, and ASCE 31-03.

Existing Buildings

Seismic Evaluation of Existing Buildings that have been designed and constructed prior to the recent the International Building Code (IBC) and International Residential Code (IRC) can be evaluated against the ASCE/SEI 31-03 code. This provides a three-tiered process for seismic evaluation of existing buildings to determine whether a building is adequately designed and constructed to resist seismic forces. The performance of the building performance looks at the structural, nonstructural, and foundation/geologic hazard issues. Reference is made back to the last release of the Uniform Building Code (UBC) which was published prior to the release of the IBC and IRC codes. Our staff is familiar with effectively implementing the requirements to provide the Life Safety or Immediate Occupancy Performance Level provisions for the structure.

Commercial Buildings

The seismic evaluation of commercial structures will follow a hybrid approach to our descriptions previously mentioned for the Residential Homes and Existing Buildings. Because the structure may be new or existing, similar procedures are implemented based on the construction of the building. For each approach the appropriate building codes will be implemented to provide the most cost-effective solution.

Bridges

The seismic analysis of bridge structures will be under the direction of the local jurisdiction, and will likely follow the provisions set by the American Association of State Highway and Transportation Officials (AASHTO). Primarily, the seismic analysis will evaluated the soil-structure interactions, and the developed behavior will provide a very important role to the seismic response of bridge. Depending on the type of bridge structure, a linear or non-linear approach will be taken. The backfill of soil around the abutments can be a primary contributor to the loads considered in the longitudinal direction of the bridge. Deep foundations can be controlled by whether soil liquefaction is present. Whether it is a new or existing structure, we have the experience to incorporate the necessary parameters to fully analyze the bridge.

Retaining Walls

As with the seismic analysis of bridge structures, the approach to analyzing retaining walls for earthquake loads will follow a similar approach similar to a bridge abutment. Again, the analysis will be under the direction of the local jurisdiction, and will likely follow the provisions set by the American Association of State Highway and Transportation Officials (AASHTO). The seismic analysis will evaluate the soil-structure interaction between the retaining structure and the soil it needs to retain. The typical analysis will follow a linear approach with design loadings according to the Coulomb or Rankine theory for static loads and the Mononobe–Okabe theory for seismic loads.