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Title: Formulation of Optimal Strut-and-Tie Models in Design of Reinforced Concrete Structures

Author(s): M. A. Ali and R. N. White

Publication: Symposium Paper

Volume: 193


Appears on pages(s): 979-998

Keywords: beam; concrete (reinf orced); strut; tie

DOI: 10.14359/9971

Date: 8/1/2000

A new design capability for automated formulation of optimal truss models (strut-and-tie models) is presented and illustrated with example designs of a variety of disturbed regions of reinforced and pre-stressed concrete structures, including deep beams with holes, continuous beams, and comer joints. The design method selects the optimal geometry of the strut-and-tie layout, determining the proper positioning of tensile ties and compressive struts to minimize the amount of reinforcing steel needed in the tension ties of the truss model for the region being designed. Two practical parameters are under control of the design engineer running the computer program-a reinforcement layout practicality factor which can be used to force the reinforcement layout into strictly horizontal and vertical bars (which will require additional reinforcement volume beyond the true optimal value), and a stress redistribution factor which can be used to control the amount of redistribution needed in developing the full capacity of the truss model after cracking has occurred.