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Sizer generates a comprehensive set of load combinations according to ASCE 7 sections 2.4 for ASD design and 2.3 for LRFD design. The combinations include the following load types - live, dead, wind, snow, earthquake, storage live, roof live and impact.
In Concept mode, vertical load distribution is done independently for each load type, and the resulting loads are combined on each member.
Concentrated Load Combinations
The specified concentrated live load is considered to act in place of any live (occupancy) load for all load combinations (except patterns) specified by the code. The program verifies all of the load combinations it ordinarily does, plus those combinations derived by replacing the live occupancy loads in those combinations by the concentrated live load at one-foot increments along the member, creating a separate series of load combinations.
The main concentrated load combinations comprised of the moving concentrated load combined with the self-weight and the other non-live loads present on the beam are shown in the list of Load Combinations in the Analysis results. The "virtual" combinations created at one-foot intervals are only shown if they are critical for design.
IBC Exceptions
IBC 1605.1 refers to ASCE 7 2.3 and 2.4 for load combinations to be used, and adds three Exceptions.
Exception 1 pertains to specific calculations for seismic damping systems and soil-structure interaction and is not implemented by Sizer.
Exceptions 2 and 3 apply only to ASD design and are discussed there.