Abstract

More precast concrete structures have recently been constructed due to their many advantages when compared to conventional cast-in-place construction. Structural behavior at the joints between the precast segments can significantly affect the overall integrity, safety, and serviceability of the structure. In this study, therefore, the interface shear strength of high-strength precast members was investigated by performing push-off tests with the following variables: compressive strength of precast members, dry or wet joint, number and height of shear keys, joint width, filler type, curing temperature, and lateral compressive stress. The test results were analyzed to reveal the effect of each test variable on the joint shear strengths of the specimens. For instance, the failure loads were increased by 14–140%, depending on the lateral compressive stress, as the specified compressive strength of the precast members was increased from 80 to 150 MPa in the dry joints. The failure loads of the wet joints strongly depended on the strength of the filler rather than on that of the precast members and, as a result, the specimen with ultra-high-strength concrete filler was 46–48% stronger than those with high-strength mortar filler. The shear strengths of various joint types obtained from the test were further analyzed in comparison with the predictive equations of Japan Society of Civil Engineers (JSCE) and American Association of State Highway and Transportation Officials (AASHTO) with the aim of validating the appropriateness of these design provisions. In particular, an improved value of a coefficient in the JSCE equation is proposed to cover a range of compressive strengths in various precast members and filling materials.

Highlights

  • The strength of concrete has been greatly increased over the last few decades and high-strength concrete with a compressive strength over 55 MPa, according to ACI Committee 363, has become common [1]

  • Thevariables test variables were compressive of precast members, dry or wet joint, number and height of shear keys, joint width, filler type, strength of precast members, dry or wet joint, number and height of shear keys, joint width,curing filler temperature, and lateral compressive stress

  • Strainand gauges and displacement were the specimens, any analysis of the measured strains and displacements was beyond the scope of our installed on the specimens, any analysis of the measured strains and displacements was beyond the study, of in our which the failure loads shear strengths were the primary scope study, in which the and failure loads and shear strengths wereconcern

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Summary

Introduction

The strength of concrete has been greatly increased over the last few decades and high-strength concrete with a compressive strength over 55 MPa, according to ACI Committee 363, has become common [1]. Materials 2020, 13, x FOR PEER REVIEW can dividedspace into two wet, where the joint has a in-place, certain space filledwhere by casting a selected has be a certain filledtypes: by casting a selected material and dry, the match-cast material in-place, and dry, where the match-cast surfaces of the two segments are in direct contact surfaces of the two segments are in direct contact with the optional application of epoxy between the with the optional application ofincrease epoxy between surfaces This epoxy is known increase the surfaces. Thevariables test variables were compressive of precast members, dry or wet joint, number and height of shear keys, joint width, filler type, strength of precast members, dry or wet joint, number and height of shear keys, joint width,curing filler temperature, and lateral compressive stress. An improved form of the predictive a wide range of compressive strengths, including high strength and ultra-high strength, in precast was proposed to cover a wide range of compressive strengths, including high strength and ultra-high members and fillers.members and fillers

Test Specimens
Mix proportion of precast
Dimensions
Set-up
Failure Mode
Number
Height of Shear Key
Presence of Epoxy
Compressive Strength of Precast Concrete
Lateral
Filler Type
Curing Temperature
Joint Width
Comparison between Dry Joint and Wet Joint
General Remarks
Comparison with the AASHTO Equation
Comparison with the JSCE Equation
Findings
Conclusions
Full Text
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