Title: Evaluation of Load Transfer and Strut Strength of Deep Beams with Short Longitudinal Bar Anchorages

Author(s): Sergio F. Brena and Nathan C. Roy

Publication: Structural Journal

Volume: 106

Issue: 5

Appears on pages(s): 678-689

Keywords: anchorage length; deep beams; strength; strut-and-tie models

DOI: 10.14359/51663108

Date: 9/1/2009

Abstract:
This paper presents laboratory results of 12 deep beams in which the longitudinal reinforcement was anchored into the support using short straight bar anchorages. The shortest anchorage lengths provided were below 50% of those required by ACI 318-08 Chapter 12 provisions. Four different specimen groups were constructed using three different shear span-depth ratios (a/d) and two longitudinal bar sizes. Most of the beams failed by strut crushing after yielding of the main longitudinal reinforcement at midspan. Only those specimens with the shortest anchorage length in each group developed concrete splitting failures along the anchorage region. The effect of a/d and anchorage length on strut strength and load transfer mechanism observed in the tests is presented and discussed. Test results indicate that a significant portion of the applied shear force may be transferred through truss action even in beams with low a/d. In addition to well-known variables such as a/d and transverse reinforcement content, short anchorage length affected the load transfer characteristics of the deep beams tested in this research.