SEIMIC SEPARATION BETWEEN TWO BUILIDINGS BY CODE 2

[bernardoporta]

I NEED TO KNOW IF THERE IS ANY U.S. BUIDING CODE THAT ADDRESSES THE ISSUE OF MINIMUM SEPARATION BETWEEN TWO BUILDINGS, ESSENTIALLY FOR SEISMIC REASONS, AND IF SO, WHAT IS THE VALUE OF THIS SEPARATION. THANKS

 

[DST148]

Refer IBC 2003, section 1620.4.5 Building Separations

 

[hawkaz]

ASCE7 12.12.3 All portions.... separated structurally by a distance sufficient to avoid damaging contact under total deflection as determined in Section 12.8.6.

 

[ishvaaag]

ASCE 7-10 at C15.1.3

SEISMIC DESIGN REQUIREMENTS FOR NONBUILDING STRUCTURES
Structural Analysis Procedure Selection

"2. Arrangement of supported masses: Despite their potential building-like appearance, not all nonbuilding structures are building-like in terms of how the attached masses are supported. For example, the response of nonbuilding structures composed of suspended vessels and boilers cannot be reliably determined using the equivalent lateral force procedure because of the pendulum mode shape(s) associated with the signifi cant mass of the
vessel/boiler. The resulting pendulum mode shape(s), while beneficial in terms of reducing the demand for story shears and base shear, may pose a problem in terms of providing sufficient clearances to allow pendulum motion of the supported vessel/boiler or piping. Dynamic analysis should be performed in such cases, with consideration for appropriate impact forces in the absence of adequate clearances."

Just on finding that in the commentary for appurtenances implies that as a minimum for complete buildings, the probabilistic estimate of the maximum inelastic response displacement must be taken as a minimum clearance if to dismiss pounding action.

This is confirmed in ASCE 7-10

"12.12.3 Structural Separation
All portions of the structure shall be designed and constructed to act as an integral unit in resisting seismic forces unless separated structurally by a distance suffi cient to avoid damaging contact as set forth in this section.

Separations shall allow for the maximum inelastic response displacement (δM). δM shall be determined at critical locations with consideration for translational and torsional displacements of the structure including torsional amplifi cations..."

So there is a mandate of evaluation of response displacement to prevent pounding. This is an inferred, if not express, ordnance for distance between buildings.

One can assume that there may be different counties or cities, towns, villages, may have decided to give express distances between buildings to prevent pounding, on some basis, kind of construction, quarter etc.

Within the scope of the simplified calculation of section
12.14.8 Simplified Lateral Force Analysis Procedure

the explicit drift evaluation may not even be required...

"12.14.8.5 Drift Limits and Building Separation
Structural drift need not be calculated. Where a drift value is needed for use in material standards, to determine structural separations between buildings or from property lines, for design of cladding, or for other design requirements, it shall be taken as 1 percent of structural height, hn, unless computed
to be less."

For seismically isolated structures...

"17.2.5.2 Building Separations
Minimum separations between the isolated structure and surrounding retaining walls or other fixed obstructions shall not be less than the total maximum displacement."

Again the incidences found by searching within the ASCE 7 pdf document for pounding, clearance and separation.