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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 17 Abstracts search results
Document:
SP133-11
Date:
September 1, 1992
Author(s):
Alex Aswad
Publication:
Symposium Papers
Volume:
133
Abstract:
A procedure for rational prediction of deformation in pretensioned members is described. Full-scale load tests on stemmed members spanning 30 to 62 ft (9.2 to 18.9 m) were conducted by the author. They showed good correlation with the proposed predictions. Actual deflections were generally less or close to the computed values. It is suggested that the method may be used for loads not exceeding a certain ratio of the ultimate loads.
DOI:
10.14359/2888
SP133-09
Shivaprasad T. Kudlapur and Edward F. Nawy
Studies are limited on the early age performance of high-strength cold weather concretes and their shear strength interaction in cold weather. This paper presents shear transfer strength characteristics between regular high-strength concrete and (i) methyl methacrylate-based polymer concrete and (ii) magnesium phosphate based concrete in subfreezing temperatures. Analytical expressions were developed based on shear transfer hypothesis and verified by experimental results. The experimental study included tests on cylinders and L-shaped push off specimens to determine the early age shear interlock and shear frictional resistance between high-strength regular portland cement concrete and cold weather high-strength concretes as is experienced in rehabilitation of bridge decks and other infrastructure systems. Studies indicated that at early age of 24 hours, shear transfer strength of 1400 psi can be obtained with the use of appropriate material and shear reinforcement. The study also indicated the ACI 318-89 code limits on the shear-friction strength are too conservative even at early ages for high-strength cold weather concretes.
10.14359/2872
SP133-10
Sami W. Tabsh
Concrete bridges in the United States constitute about fifty percent of the total number of highway bridges. Recent studies indicate that many of these bridges deteriorate due to age, corrosion of reinforcement, fatigue, cracking and spalling of concrete, and/or human error. Limited funds are available for rehabilitation, strengthening, and replacement. Therefore, there is a need for methods to identify the parts of concrete girder bridges most sensitive to damage using reliability models. This may help lower the costs of checking, inspection, and repair. Load and resistance sensitivity functions for the ultimate flexural capacity limit state of simply supported bridge girders are included. The study indicates that the reliability of bridge girders depends mostly on the strength and location of steel.
10.14359/2875
SP133-16
Howard H. M. Hwang and Hui-Mi Hsu
This paper presents the evaluation of seismic performance of a special moment-resisting (SMR) frame building and an intermediate moment-resisting (IMR) frame building designed in accordance with the NEHRP provisions and ACI Code 318-83. The annual limit-state probabilities for both SMR and IMR frames are determined by integrating the seismic hazard curve and structural fragility curve. From the comparison between the calculated annual limit-state probability and the specified acceptable risk levels, the seismic performance of a structure can be evaluated. In the NEHRP provision, if reinforced concrete frames are used to resist earthquake forces, the SMR frame is required for buildings belonging to higher seismic performance categories such as Categories D and E. Even though the SMR frame has a higher ductility than the IMR frame, the SMR frame is only designed for 50 percent of the strength required for the IMR frame. As demonstrated in this study, the IMR frame may perform better than the SMR frame in the event of an earthquake. Thus, the concept employed in the NEHRP provisions to protect high-risk and essential buildings needs careful reexamination.
10.14359/3062
SP133-13
C. C. Fu , J. Colville, and D. R. Schelling
Purpose is to present a lesson learned from the findings of the Governor Thomas Johnson Memorial Bridge, Maryland. The bridge has an overall length of 7205 ft, with 59 spans. Thirty-eight piers are made of concrete hammerhead-type pier caps with different height and cap sizes. The cracks observed on the deep water piers initiated the evaluation of these hammerhead-type pier caps. The structural integrity was questioned and several analysis procedures were taken on this case. Extensive computer analyses, including nonlinear finite element analyses were conducted. This paper also intends to depict the implementation of the Code, design methodology, and calculation procedures concerning this type of pier for engineering practices. Finally, the remedial strengthening method using the post-tensioning system is presented.
10.14359/2894
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