SAC Technical Studies

Task Number: 5.3.1a
Task Title: Assess and Improve Finite Element/Fracture Models for Unreinforced and Cover Plated Connection Details
Topical Area: Topical Investigations on Connection Performance
Subcontractor: Anthony Ingraffea and Gregory Deierlein, Cornell University

Task Summary:

    This task investigates the viability of existing analytical procedures that explicitly consdier crack initiation and propagation to predict connection performance of unreinforced "pre-Northridge" connections that proved to be susceptible to fracture and exhibited a number of different fracture propagation paths.

    The basis of these initial analyses will be a series of three connection tests that were performed as part of Phase 1 of the SAC Project. The initial analyses will investigate the ability of the available analytical techniques to predict the observed performance. Since the initial analyses will be performed on the available two dimensional a (2D) analysis tools, three dimensional (3D) inelastic finite element method (FEM) models will be developed to assess the importance of 3D effects on the distribution of strains and stresses in critical regions.

    Following these initial analyses, the models will be extended to observe the effect of various design parameters on the predicted performance. Parameters such as material yield strengths in various directions, material toughnesses, filler metal yield and toughnesses, weld flaw size, etc., will be varied over the range of expected available values to identify their importance to the connection performance. In addition items such as panel zone yielding, weld backing removal, weld run-off tab removal, web connection detail, residual stress distribution, etc., will also be investigated.

    This sub-task will also begin an investigation of the fracture sensitivity of the cover plated connection detail using a previous analysis of a SAC Phase 1 test as the analytical basis. Parametric studies will also be performed on this model.

Detailed Workstatement:

The detailed breakdown of the technical activities in this task are provided in the workstatement available here.
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