Strut-and-tie model design provisions

The overall objective of the research project summarized in this paper was to develop simple and safe design guidelines for deep beams. To accomplish the research objective and related tasks, a database of 868 deep-beam tests was assembled from previous research. In addition, 37 beams were fabricated and tested with the following cross-sectional dimensions: 36 in. × 48 in. (910 mm × 1220 mm), 21 in. × 75 in. (530 mm × 1910 mm), 21 in. × 42 in. (530 mm × The overall objective of the research project summarized in this paper was to develop simple and safe design guidelines for deep beams. To accomplish the research objective and related tasks, a database of 868 deep-beam tests was assembled from previous research. In addition, 37 beams were fabricated and tested with the following cross-sectional dimensions: 36 in. × 48 in. (910 mm × 1220 mm), 21 in. × 75 in. (530 mm × 1910 mm), 21 in. × 42 in. (530 mm × 1070 mm), and 21 in. × 23 in. (530 mm × 580 mm). These tests represent some of the largest deep-beam shear tests ever conducted. Based on an analysis of the database and the experimental program, the deepbeam shear provisions in Building Code Requirements for Reinforced Concrete (ACI 318-08) and AASHTO LRFD Bridge Design Specifications were found to be overly conservative. Thus, a new and simple strutand-tie modeling (STM) procedure was proposed for the strength design of deep-beam regions. The procedure is largely based on the fib structural concrete design provisions. It is more accurate than the STM design method in ACI 318-08 and AASHTO LRFD specifications but just as conservative. With the use of the proposed provisions, the design of deep beams is more efficient and reliable. As a result, implementation of the new design provisions into ACI 318-08 and AASHTO LRFD specifications is recommended.