IBC


The EQ-Force process is the only earthquake process which
 reduces the seismic force on a footing and decreases damage to the structure.



Designing under the IBC

With the US having adopted the International Building Code (IBC) and most states having adopted it, designing structures will have entered a new era and the forms of analysis will be different. In studying this subject for the recent patent and the applicability of the process, we have sorted through the kind of information you will need to obtain, and something about the extent of proof of analysis you will need to be able to certify compliance with the earthquake provisions of the code.

We cannot assist you with the judgement calls which you will have to make concerning the category of risk, the type of use to which a structure will be put, the hazard to people occupying the premises, and the downstream hazard to people if a structure should fail.

In late 2003, the Structural Engineering Institute of the ASCE published what will become the benchmark handbook on seismic codes. It is "Seismic Evaluation of Existing Buildings," SEI/ASCE 31-03. It presents a three tiered process for seismic evaluation of any level of seismicity. Although described as being applicable to existing buildings, it also covers the procedures for new structures and additions to existing structures. It was designed to become a nationally applicable tool, perhaps the tool, for designers, code officials, and building owners.

It provides an evaluation system concerned with the Life Safety and Immediate Occupancy Performance Level of performance in a rational and understandable way. That is quite an order, but the authors have brought it off well.

The major thrust of the manual is dedicated to providing the designer on how he should determine if a structure is adequately designed and constructed to resist seismic forces. It does not address the design of mitigation measures or give advice on what to put in.

The manual is intended to replace FEMA 310, the "Handbook for Seismic Evaluations of Buildings." All aspects of structural performance are considered and defined in terms of structural, non-structural, and foundation and geologic hazard issues. It is written to reflect advancements in technology, experience of active design professionals (advice of those who have worked with the seismic situation in recent earthquakes) to incorporate that experience in designs, to be compatible with FEMA 356 and FEMA 2000b, to be suitable for adoption in building codes and contracts, to be nationally acceptable, and to provide advice on the newest evaluation techniques.

It’s an expensive report: $112.50 for ASCE members and $150.00 for non-members. But if you are a designer of structures, you can hardly be without it. Nor can code officials and major owners be without it.

All this frenzy of a new type of analysis began about ten years ago as engineers scrutinized data from the two big recent earthquakes in California, Loma Prieta and Northridge. Designers began to incorporate all elements of a structure into the requirements imposed by living on the faults. The building, its footings, and its underpinnings are now being considered in unison with the steel and concrete. The whole business of putting up something new or retrofitting the old is being treated as a unified system.

Tall structures were the first to succumb to this analysis. If a building is tall enough, and you make it flexible enough, it will simply sway with seismic or wind forces. If it is on a floating foundation or shallow footing, a mini-piling system can contribute to the stability of the building as compared to caissons. If it is on liquefiable soils which are not too deep, the EQ-Force array may lower your cost and raise safety at the same time. The soil, footings, and building are treated as one. This is the new era.

Incorporated in the reference section of this site, are several good sources which summarize the new code requirements. In November 2002, "Structure" magazine made a short summary. In October and November of 2002, "Structural Engineer" magazine did the same in a more technical fashion. The same authors, Ghosh and Henry, have added another clearly stated summary of called "Earthquake Effects" in the January 2004 issue which covers regional impacts of the IBC on seismic design.






Seismic Evaluation of Existing Buildings, SEI/ASCE 31-03, Published: 2003, American Society of Civil Engineers, is a good book to getting started. It provides a three-tiered process for seismic evaluation of existing buildings in any level of seismicity. Buildings are evaluated to either the Life Safety or Immediate Occupancy Performance Level. This standard serves as a nationally applicable tool for design professionals, code officials, and building owners.

Click here to further review and/or buy the book at the ASCE (American Society of Civil Engineers) website.

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