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Topics In Concrete
Home > Publications > International Concrete Abstracts Portal
Showing 1-5 of 189 Abstracts search results
Document:
23-334
Date:
December 1, 2024
Author(s):
Christopher Wilkes, Fragkoulis Kanavaris, Chris Barker, and Duncan Nicholson
Publication:
Materials Journal
Volume:
121
Issue:
6
Abstract:
This paper presents a method for simply qualifying the practical risk of casting deep foundations based upon a combination of the behavior of the fresh concrete through testing and the confinement conditions of the foundation from a design perspective. A framework to qualify which aspects of the tremie process lead to defects is developed for the first time. Flow behavior, confinement conditions, and free-water availability are identified as key contributors to specific defects present within tremie concrete foundations. Finally, a novel risk map for tremie concrete is presented.
DOI:
10.14359/51742262
23-183
September 1, 2024
Wei Zhang and Deuckhang Lee
Structural Journal
5
Identifying plastic hinge property is one of key the factors in successful modeling and subsequent seismic performance evaluation of precast concrete (PC) moment frame systems. Tight mechanical splices are also essentially required in precast connections, and its residual slip can greatly affect the plastic hinge length and finally the emulative performance level of PC seismic forceresisting system (SFRS). However, most of the existing models are not directly applicable in current forms to estimate the plastic hinge length of precast connections with mechanical splices. To address the effects of the residual slip induced in the mechanically spliced reinforcement system and its nonuniform stiffness due to splicing device (or coupler), a detailed nonlinear finite element (FE) analysis model was developed in this study, where plasticity-based constitutive models and a unique connector element were adopted for concrete and mechanically spliced reinforcements, respectively. Existing test results of column-foundation connections were used to verify the analytical approach. On this basis, a robust macro modeling method was also proposed for nonlinear cyclic analysis of PC moment frame systems with mechanical splices in this study. It appears that the magnitude of the residual slip in mechanical splices can greatly undermine the lateral stiffness, energy dissipation capacity, and equivalent viscous damping ratio of PC moment connections, and the proposed macro modeling approach can reasonably capture their behavioral characteristics.
10.14359/51740859
22-401
G. F. Crocker, B. E. Ross, M. C. Kleiss, P. Okumus, and N. E. Khorasani
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.
10.14359/51740848
22-398
Sangyoung Han, Jarrod Zaborac, Jongkwon Choi, Anca C. Ferche, and Oguzhan Bayrak
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.
10.14359/51740847
23-207
August 1, 2024
Zhao-Dong Xu, Yi Zhang, Jin-Bao Li, and Chang-Qing Miao
4
Accurately measuring the working stress of concrete through the stress-release method is a crucial foundation for assessing the operational condition of building structures and formulating maintenance and reinforcement strategies. The slotting method, employed within the stress-release technique, not only addresses the limitations associated with the core-drilling and hole-drilling methods, but also offers a practical solution for engineering detection. This paper presents a novel multi-step slotting method employing a stress-release rate model as its foundation. The fundamental equations governing space-related issues are introduced, and a theoretical model of the stress-release rate is derived. By employing a multi-step slotting process instead of the conventional one-step slotting approach, the limitations of the traditional drilling method are overcome. The stress-release rate model is calibrated using numerical simulation outcomes, followed by both numerical simulation and experimental verification. With a relative error of 3.5% between theoretical and simulated values, and 9.4% with experimental values after excluding the initial slotting data, it is evident that the stress-release rate model demonstrates notable accuracy and applicability. This reaffirms the effectiveness and convenience of the multi-step slotting method for measuring concrete working stress.
10.14359/51740782
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