Va handbook h-18-8 seismic design requirements

See paragraph 2. However, a design professional may revoke these omissions on an individual project basis. SHL for a specific project for use of its manual. The SHL is derived from a combination of factors such as applicable building codes,. The design professional is responsible for specifying the SHL not the building contractor. Bracing in SHL "B" is designed to resist 30 percent, and in the bracing in SHL "C" is designed to resist 15 percent of the weight of the ducts or pipes.

In addition to the. Each code has its own method for determining the percent. The formulas are in the form:. Cs is a seismic coefficient, which represents a combination of factors that varies with the building code. If F Percent is greater than 48, then manual cannot be used, and an independent analysis and design is required for all bracing components. The guidelines are not intended as a substitute for design.

The design of seismic bracing remains the responsibility of the design professional, who must review the specific project for its. Transfer beams or trusses supporting upper level columns shall not be usedunless permitted on a case by case basis by VA. Seismic joints shall be avoided, in so far as possible. When required, they shallbe specifically identified in the schematic design phase of the project andapproved by VA, subject to the following provisions Seismic joints shall be properly detailed on the working drawings;2.

Seismic joints shall be sized based on the maximum expecteddisplacements, considering the effects of story drift, diaphragmdisplacements and rotations, and a realistic approximation of elementsection properties. For materials designed considering the ultimate limitstate, such as concrete, the stiffness representative of this state shall beused.

Adjacent structures that are not integral with an existing structure shall beseparated by not less than 2 inches per story. Prestressed concrete structural members, including pre-tensioned and posttensioned members, and precast elements such as tilt-up wall panels, andprecast beam and column elements shall not be used to resist seismic forces.

Lightweight concrete shall not be used in structural members resistingearthquake forces, except in concrete floors and roof slabs used as diaphragmelements to distribute earthquake forces to vertical lateral-load resistingelements. Steel eccentrically braced systems shall be subject to the following specialprovisions Connections of non-structural elements shall not be located in the vicinity ofEBF link beams.

Non-structural elements include, but are not limited to, precast panel connections, elevator guide rail supports, stairs, and pipesupports, etc. No action regarding seismic rehabilitation of the seismic force resisting systemof existing buildings need be undertaken in regions of moderate-low and lowseismicityb. Non-structural components shall comply with the requirements of section 4. Exceptions: Seismic restraint may be omitted for the following installations:a. Gas and medical piping less than one inch inside diameter;b.

All rectangular air handling ducts less than six square feet in cross sectionalarea;f. All round air handling ducts less than 28 inches in diameter;g. All ducts suspended by hangers 12 inches or less in length from the top of theduct to the bottom of the support for the hanger;h.

Equipment weighing less than lbs, supported and attached directly on thefloor; andi. Equipment weighing less than 20 lbs suspended from the roof or floor or hungfrom the wall. Except in regions of low seismicity, the geotechnical investigation shall useappropriate methods to allow the most accurate evaluation of the site class inaccordance with Chapters 20 and 21 of ASCE 7, including field shear wavevelocity measurements. The report shall contain data that provide an assessment of thenature of the site and potential for earthquake damage based on preliminaryinvestigations of the regional and site geology, subsurface conditions and thepotential seismic shaking.

The engineering geologic report shall not contain designcriteria, but shall contain basic data to be used for a preliminary earthquakeengineering evaluation of the project. The basis for seismic assessment in geologichazards reports must be stated clearly.

The report shall include, but shall not be limited to the following:a. Geologic investigation;b. Identification of any known active and potentially active faults, both regionaland local, including estimates of the peak ground accelerations that could occurat the site; andc. Evaluation of any slope stability problems at or near the site, liquefactionpotential and settlement potential of the building site. VA shall approve the engineering geologic hazard report prior to the preparation ofthe geotechnical report.

The characteristics of the expectedstrong ground motion to be used in design shall be determined by site evaluationstudies based on geological and seismological characteristics of the site, includingdata given in the engineering geologic hazards report.

The estimates should bederived by accepted methods of seismological practice, including Next GenerationAttenuation NGA relationships where applicable, and fully documented in theground response report. The level of ground motions to be developed shall bedetermined using the procedures in Chapter 21 of ASCE 7.

VA shall approve the site-specific ground response report prior to its adoption forproject design. Section 2. This has now beenseparated and has different design requirements.

Section 3. Lines of lateral force resistance shall be located at major areasof plan irregularity such as reentrant corners. Proposals to obtain written approvalfor other structural systems shall demonstrate the value of those systems, relativeto the permitted systems, considering a initial construction and maintenancecosts, b requirements for bracing non-structural components and buildingcontents, c risk of economic losses and disruption to hospital functions due toearthquakes and d other demonstrable benefits.

Section 5. Except in regions of low seismicity, an accurateevaluation of site class is to be made in accordance with Chapter 20 and Chapter21 of ASCE 7 and is to be presented in the geotechnical evaluation report.

Fieldshear wave velocity measurements are typically expected to provide the mostreliable basis for an accurate evaluation of site class. Although site-specific studies exi. Seismic joints shall be sized based on the maximum expected displacements, considering the effects of story drift, diaphragm displacements and rotations, and a realistic approximation of element section properties.

For materials designed considering the ultimate limit state, such as concrete, the stiffness representative of this state shall be. Export To Word. Last View : 6d ago. Last Download : 4m ago.

Upload by : Bria Koontz. Report this link. Related Books. However, seismic criteria must be addressed in this case. Seismic Bracing Systems - Power-Strut. The development of a new seismic table is required for seismic factors other than 1.