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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
SP133-13
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
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
SP133-01
Edward G. Nawy
This paper presents the state of the art in evaluating flexural crack development and control of macrocracking. It is based on extensive research over the past five decades, in the United States and overseas, in the area of macrocracking in reinforced and prestressed concrete beams and in two-way action slabs and plates With the advent of limit states theories that generally lead to economic proportioning of members, control of cracking has become essential to maintain the integrity and esthetics of concrete structures. The trend is stronger than ever in better utilization of current concrete strengths, use of higher strength concretes that include super-strength concretes of 20,000 psi (138 MPa) compressive strength and higher, and increased application of prestressed concrete concepts. All these trends require closer control of serviceability requirements in cracking and deflection. Design expressions are given for the control of cracking in reinforced concrete beams and thick one-way slabs; prestressed, pretensioned, and post-tensioned flanged beams; and reinforced concrete two-way action structural floor slabs and plates. In addition, recommendations are given for the maximum tolerable flexural crack widths in concrete elements.
10.14359/3131
SP133-02
Andrew Scanlon and Ross B. Corotis
The American Concrete Institute, Standard 318, Building Code Requirements for Reinforced Concrete have permitted the design of reinforced concrete structures in accordance with limit state principles using load and resistance factors since 1963. A probabilistic assessment of these factors and implied safety levels is made, along with consideration of alternate factor values and formats. A discussion of issues related to construction safety and safety of existing structures is included.
10.14359/3138
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