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An experimental study was performed to examine the effect of section depth on the strength and serviceability of reinforced concrete deep beams. Full-scale tests were conducted on simply supported beams with the following cross sections: 21 x 23 in. (533 x 584 mm), 21 x 42 in. (533 x 1067 mm), and 21 x 75 in. (533 x 1905 mm). Tests were performed on each section type at the following shear span-depth ratios (a/d): 1.2, 1.85, and 2.5. Diagonal cracking loads, diagonal crack widths, and shear at failure were recorded for each test. The strength results indicated that the shear capacity of a deep beam is governed by the strength of the nodal regions, which are not directly proportional to the member depth. When deep beams are designed with strut-and-tie models, the strength of the nodal regions are addressed explicitly and no depth effect on the shear capacity of the member is apparent.

This paper describes how four reinforced concrete T-beams were tested in order to study their behavior when strengthened for shear using near-surface mounted (NSM) bars. The objectives were to study the effects of the type of bars used (carbon fiber-reinforced polymer (CFRP) and conventional reinforcing steel) and the effects of the load level at which the bars are installed. It was observed that the CFRP bars bonded at zero load increased the shear capacity by up to 92%, while those bonded when the precracked beam was under load increased the capacity by 77%. For the steel bars, these values were 75% and 57%, respectively. The CFRP strengthened regions showed a slightly more favorable response than those strengthened with conventional steel bars. Strengthening provided an improved control of the diagonal crack width. In the beams with closer spacing of NSM bars, the increase in shear strength allowed the beam to fail after considerable flexural deformations.

Inverted "T" bent caps are used frequently on Texas bridges because they are aesthetically pleasing and offer a practical means to increase vertical clearance. Since the current design guidelines do not address the existing problem of crack control at service load adequately, explicit design provisions for cracking need to be developed. This research seeks to develop a serviceablity design method for controlling crack widths at the re-entrant corners of inverted "T" bent caps. The design method is based on a rational physical model and is collaborated by an extensive experimental program. The three types of specimens tested were: the 2-D specimens, 3-D specimens and whole-bent-cap specimens. Three equations are proposed to control the diagonal crack widths at the re-entrant corners of the inverted "T" bent caps. The equations are: one for crack widths at the vicinity of interior applied loads, and the other two for crack widths at the end faces of exterior spans; the equations are applicable to full size highway bridges and are suitable for incorporatiion into the AASHTO Specifications.

Often, unacceptable diagonal cracks occur at service load in the vicinity of the re-entrant corners in structures such as the dapped ends of bridge girders and the ledges of inverted T bent caps. Such diagonal cracks are not only visually intimidating but also impose potential danger of corrosion of reinforcing bars. Controlling such cracking is difficult due to the lack of a rational theory for crack prediction. This paper proposes a compatibility-aided strut-and-tie model for predicting the diagonal crack widths at re-entrant corners. The validity of this model is supported by tests of 7 full-scale specimens.

Test results of eight reinforced concrete continuous deep beams are reported. The main parameters considered were shear span-to-depth ration, amount and type of web reinforcement, and amount of main longitudinal reinforcement. Vertical web reinforcement had more influence on shear capacity than horizontal web reinforcement. Failure is initiated by a major diagonal crack in the intermediate shear span between the edges of the load and intermediate support plates. Comparisons between test results and current codes of practice, namely the ACI Building Code (318-89) and CIRIA Guide 2, show little agreement.

The structural rehabilitation of reinforced concrete beams in shear was studied with particular attention paid to resin injection. Other shear-repair techniques that were examined include post-tensioning in shear, bar bonding, and stitching. Emphasis was placed on the influence of damage across the repair stage. A series of model beams, unreinforced in shear, were loaded in the laboratory until a major diagonal tension crack developed on both shear spans. Individual beams were unloaded to a set proportion of that load, repaired, and again loaded to failure. Scaled field-size beams were also tested. The repair strength achieved for resin-injected reinforced cocnrete beams was shown to be influenced by the condition of the major diagonal crack after initial damage. This conclusion was supported by surface-strain measurements, load-deflection data, and crack measurements.

A SYSTEMATIC EXPERIMENTAL INVESTIGATION COMPRISING 12 REINFORCED CONCRETE SHORT BEAMS WAS UNDERTAKEN PRIMARILY TO DETERMINE HOW SEVERE THE CRACK WIDTH PROBLEM IS IN SHORT BEANS AND HOW THIS PROBLEM CAN BE CONTROLLED WITH A MINIMUM AMOUNT OF WEB REINFORCEMENT. TEST RESULTS INDICATE THAT FOR SHORT BEAMS CONTAINING NO WEB REINFORCEMENT, DIAGONAL CRACK WIDTHS AT WORKING LOAD LEVELS MAY PRESENT A SERIOUS SERVICEABILITY PROBLEM. IT IS SHOWN ONLY A SINGLE VERTICAL OR INCLINED STIRRUP IS REQUIRED TO CONTROL THIS SERVICEABILITY PROBLEM AND TO SIMULTANEOUSLY ATTAIN FLEXURAL CAPACITY. /ACIJ/