NEHRP Clearinghouse

Title
Three Dimensional Inelastic Frame Elements for the ANSR-I Program.
File
PB295755.pdf
Author(s)
Riahi, A.; Row, D. G.; Powell, G. H.
Source
National Science Foundation, Washington, DC., August 1978, 75 p.
Identifying Number(s)
UCB/EERC-78/06
Abstract
This report describes two elements developed to allow inelastic three-dimensional building frames to be analyzed using the ANSR-1 computer program (1). The first element is a beam-column which has two-dimensional stiffness and yield characteristics. This element may be located arbitrarily in a three-dimensional structure and is intended primarily for modelling beams. The second element is a beam-column which has three-dimensional stiffness and yield characteristics. This element can be used for modelling columns in which biaxial bending effects may be important and also for structures such as elevator shafts. Both elements assume that inelastic behavior is concentrated in plastic hinges at the element ends. For the two-dimensional element the plastic hinges are affected by moment in the principal bending plane only, or by this moment interacting with axial force. For the three-dimensional element the plastic hinges are affected by bending moments about both axes, axial force and (if desired) torsional moment. Allowance has been made for rigid floor diaphragms by means of a 'slaving' feature. This slaving feature has been incorporated into both elements at the element level because ANSR-I cannot account for slaving at the nodal level. Both elements also allow for rigid end zones and for initial element actions. The theoretical formulations are presented and the element characteristics are described. User's guides for both elements are included and an example analysis is described.
Keywords
Computer programming; Buildings; User needs; Earthquake engineering; Beams (Supports); Earthquakes; Frames; Stiffness; Inelastic behavior; Columns (Supports); Deformation; ANSR-1 computer program; Bending moments