International Concrete Abstracts Portal

Showing 1-5 of 147 Abstracts search results

Document: 

22-398

Date: 

September 1, 2024

Author(s):

Sangyoung Han, Jarrod Zaborac, Jongkwon Choi, Anca C. Ferche, and Oguzhan Bayrak

Publication:

Structural Journal

Volume:

121

Issue:

5

Abstract:

The results of an experimental program conducted to evaluate the performance of shear-critical post-tensioned I-girders with grouted and ungrouted ducts are presented. The experimental program involved the design, construction, and testing to failure of six fullscale specimens with different duct layouts (straight, parabolic, or hybrid) and using both grouted or ungrouted ducts. All tests resulted in similar failure modes, such as localized web crushing in the vicinity of the duct, regardless of the duct condition or layout. Furthermore, the normalized shear stresses at ultimate were similar for the grouted and ungrouted specimens. The current shear design provisions in the AASHTO LRFD Bridge Design Specifications (AASHTO LRFD) were reviewed, and updated shear-strength reduction factors to account for the presence of the duct in the web and its condition (that is, grouted or ungrouted) were proposed. The data generated from these tests served as the foundation for updated shear-strength reduction factors proposed for implementation in AASHTO LRFD.

DOI:

10.14359/51740847


Document: 

22-401

Date: 

September 1, 2024

Author(s):

G. F. Crocker, B. E. Ross, M. C. Kleiss, P. Okumus, and N. E. Khorasani

Publication:

Structural Journal

Volume:

121

Issue:

5

Abstract:

This paper describes the experimental testing of a reinforced concrete tessellated shear wall. The wall specimen was tested as part of a National Science Foundation-funded research project designed to demonstrate the concept of tessellated structural-architectural (TeSA) systems. TeSA systems are constructed of topologically interlocking tiles arranged in tessellations, or repeating geometric patterns. As such, these systems are designed with easy repair and reuse in mind. The specimen discussed in this paper is a TeSA shear wall constructed from individually precast I-shaped tiles. This paper presents the results of reverse cyclic loading of the specimen, including load-displacement behavior, crack propagation, and energy dissipation. A simplified analytical model for predicting the wall’s flexural capacity is also discussed.

DOI:

10.14359/51740848


Document: 

22-384

Date: 

March 1, 2024

Author(s):

Julian D. Rincon, Yu-Mei Chen, Santiago Pujol, Aishwarya Y. Puranam, and Shyh-Jiann Hwang

Publication:

Structural Journal

Volume:

121

Issue:

2

Abstract:

An alternative method to retrofit reinforced concrete (RC) columns with insufficient shear reinforcement is investigated. The retrofit involves external prestressing of the columns in the transverse direction to increase both shear strength and drift capacity. External post-tensioned clamps, consisting of high-strength steel rods connecting a set of steel angles, were applied around the columns at different spacings and initial post-tensioning stresses. The tension induced in the steel rods exerts lateral confining pressure on the column by bearing of the angles against the corners of the column. Ten RC columns furnished with external post-tensioned clamps were tested under cyclic loads and approximately constant axial loads. In addition, six RC beams with clamps were tested under monotonically increasing loads. Both the column and beam specimens were fabricated with no transverse reinforcement in the form of conventional steel ties. Therefore, the external clamps were the only source of reinforcement resisting shear. The lateral prestress provided by the clamps was observed to increase the shear stress at the formation of the first inclined crack and at failure. As a result, the mode of failure of columns vulnerable in shear changed from shear failure to a more ductile failure dominated by flexure. The observed increase in shear strength is dependent on the lateral prestress and the tensile strength of the concrete. A simple equation, based on the mechanics of materials, is presented to calculate the shear strength of RC columns with external prestressing.

DOI:

10.14359/51740248


Document: 

22-034

Date: 

January 1, 2024

Author(s):

Hyeon-Keun Yang and Hong-Gun Park

Publication:

Structural Journal

Volume:

121

Issue:

1

Abstract:

To investigate the effect of prestressing on the shear strength of nuclear power plant containment structures, five reinforced or post-tensioned semi-cylindrical concrete walls and two planar walls were tested under cyclic lateral loading. The major test parameters were the presence of unbonded post-tensioning, the magnitude of horizontal prestressing force, and the use of crossties. The test results showed that because of the high reinforcement and prestressing ratio, web-crushing failure occurred in all specimens. The shear strengths of reinforced concrete (RC) and prestressed concrete (PSC) walls were greater than the nominal shear strength specified in the current design/evaluation methods. In the case of walls subjected to horizontal prestressing force, early delamination cracking occurred due to radial tensile stress. The delamination cracking was restrained by the use of crossties. Further, the effect of prestressing on the web-crushing strength was not significant. When the diameter of the cylindrical wall was the same as the length of the planar wall, the peak shear strength of the cylindrical wall was equivalent to that of the planar wall despite the different wall shape.

DOI:

10.14359/51739182


Document: 

22-156

Date: 

November 1, 2023

Author(s):

Sanghee Kim, Thomas H.-K. Kang, Donghyuk Jung, Byung Un Kwon, and Dong Joo Lee

Publication:

Structural Journal

Volume:

120

Issue:

6

Abstract:

This paper presents experimental results on seismic behaviors of post-tensioned (PT) monolithic exterior beam-column connections. Lateral cyclic loading tests were carried out for six fullscale exterior beam-column joint subassemblies fabricated with normal- and high-strength materials. Despite substantial joint cover spalling, the normal-strength specimens exhibited satisfactory lateral strengths and hysteretic behaviors up to ±5% drift ratios by virtue of the confinement effect of post-tensioning. The high-strength PT specimens also showed stable hysteretic behaviors with significantly reduced joint damages. It was found that the post-tensioning can increase the joint shear strength by more than 60% in both types of specimens. Furthermore, the post-tensioning was effective in retaining the lateral stiffness of the beam-column joints under the repeated loads, especially in high-strength specimens, enabling them to maintain at least 90% of their first-cycle stiffnesses throughout the testing.

DOI:

10.14359/51739085


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