Civil Engineering ETDs

Publication Date

5-12-1971

Abstract

The objective of this research Kas to develop behavioral equations for reinforced concrete deep beams especially in the realm of shear capacity. A series of static and dynamic beam tests was performed to aid in the develop­ment of this objective.

Static testing was completed on nine uniformly loaded reinforced concrete deep beams. Span-to-depth ratios varied from 1.6 to 3.3. Intermediate-grade ASTM A 15 reinforcing steel was used. Nominal concrete strength was 3,750 psi. All beams contained longitudinal tensile reinforcing and no compressive reinforcing. Five beams contained an orthogonal array of web reinforcing coincident with the longitudinal axes of the beams and the other four contained no web reinforcing.

All statically tested beams were loaded to failure. There were no beams that failed prior to beam yield. Failure modes were predominantly flexure in beams with orthogonal web reinforcing and shear in those without web reinforcing.

Static shear behavior equations for deep beams were derived on the lower boundary of reinforced concrete deep beam data represented by research from this report and other research comprising 73 tests. Equations for a total static shear capacity are given which conservatively predict shear capacities of the beam tests considered. Web reinforcing capacity was considered where the web reinforcing was an orthogonal array of reinforcing coincident with the longitudinal axis of a beam.

Methods are presented for calculating moment capacity of reinforced con­crete deep beams. Conventional ultimate load theory is used with accountabil­ity for large ultimate concrete strains and nonplanar sections.

Dynamic testing was completed on three uniformly loaded reinforced con­crete deep beams. Only one span-to-depth ratio was considered, L/d = 1.6. Intermediate-grade AS'IM A 15 reinforcing steel was used. Nominal static concrete strength was 4,500 psi. All beams contained longitudinal tensile reinforcing and no compressive reinforcing. All beams contained varying amounts of orthogonal web reinforcing coincident with the longitudinal axes of the beams.

All dynamically tested beams had an air shock traverse the span where the air shock load was uniformly transferred to the compression flange of the beam. Each beam was loaded twice with approximately equal high-intensity shock loads.

None of the dynamic beams was taken to complete failure. All modes of failure were inferred from static test results and post-test examination of the dynamic test beams. All dynamic beams had probable flexural failures and behaved similarly in crack formation to companion static test beams.

Dynamic shear behavior equations for deep beams were derived on the lower boundary of data represented by research from this report and other research comprising 12 dynamic tests. Equations for a total dynru.1ic shear capacity for a first cycle loading are given which conservatively predict shear capacities of the beam tests considered. Web reinforcing capacity was considered where the web reinforcing capacity was ell orthogonal array of reinforcing coincident with the longitudinal axis of a beam.

Dynamic flexural response indicated that plane sections prior to bending do not remain plane after bending. In this type of dynamic test nonplanar sections must be accounted for in moment of resistance calculations for deep beams in the strain hardening region.

Natural periods of vibration 1r,1cre calculated for the deep beams of this report. Using the assumption of ell equivalent single-degree-of-freedom system and calculating the natural period from the measured dynamic beam response give reasonable results compared to the natural period calculated by an energy method using measured beam properties.

Document Type

Dissertation

Language

English

Degree Name

Civil Engineering

Level of Degree

Doctoral

Department Name

Civil Engineering

First Committee Member (Chair)

Cornie Leonard Hulsbos

Second Committee Member

Eugene Milton Zwoyer

Third Committee Member

Lambert Herman Koopmans

Fourth Committee Member

Roy Linton Johnson

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