Full Session with Abstracts
This presentation gives an overview of Chapter 4 of the new Alternative Load Path Analysis Guidelines, which are being developed by the Disproportionate Collapse Technical Committee of ASCE-SEI. Chapter 4 presents how commercial structural analysis and design software can be used to determine if a structure is likely to resist disproportionate collapse. It covers analysis methodologies and modeling issues, for design using the alternative load path method against disproportionate collapse.
The primary focus of this chapter is on modeling and analysis using common software such as SAP2000, STAAD.PRO, SAFE, and RAM structural system etc. Analysis methodologies, including available modeling elements, types of nonlinearities, and methods to account for the dynamic effects, are discussed. Multiple examples are provided in this chapter for various pre-defined structure types, including steel moment and gravity frames, concrete moment frames and flat plates. Examples are presented for component and sub-system levels, as well as full buildings, under various collapse scenarios.
This chapter explores force control and deformation control methods employed in linear and nonlinear static analysis, and use of plastic-hinges in non-linear models. Energy methods are included. In addition, modeling issues, such as practical limitations of the finite element formulations and difficulties in modeling slabs, are discussed.
KEY WORDS: Disproportionate collapse, Analysis and design software, Deformation control, Force control, Plastic-hinge, Load increase factor, Dynamic increase factor.