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: 

SP133-08

Date: 

September 1, 1992

Author(s):

Irfan A. Alvi and bilal M. Ayyub

Publication:

Symposium Papers

Volume:

133

Abstract:

In virtually all areas of structural engineering, including the increasingly well-known area of structural reliability assessment, it is commonly assumed that failures will occur suddenly and instantaneously in given failure modes. This assumption affords a valuable simplification of complex real-world problems. However, many failure modes do not obey this assumption, including most serviceability failure modes, strength failure modes of ductile component and/or redundant systems, and failure modes based on cumulative damage. For these cases, a formulation is required with which the transition from complete survival to complete failure can be modeled as being gradual and continuous, and comprised of partial failure levels. This paper proposes such a formulation along with corresponding methodologies for structural reliability assessment and reliability-based design. Various statistical and entropy-based measures which can be used to help characterize the results of the structural reliability assessment are also suggested. Application of the proposed structural reliability assessment and reliability-based design methodologies is illustrated with an example problem involving deflection failure of a reinforced concrete beam. Some potential applications of the proposed methodologies include probabilistic design and code calibration for failure modes modeled as having gradual and continuous failure transitions.

DOI:

10.14359/2867


Document: 

SP133-04

Date: 

September 1, 1992

Author(s):

R.S. Fling

Publication:

Symposium Papers

Volume:

133

Abstract:

This paper reviews the development of deflection calculation procedures and comments on the risk of computational errors. It then discusses practical considerations affecting deflection and their limitations. It assesses the effect of nine parameters on the variability of deflection by reference to two example beams. Finally, the paper recommends further laboratory and analytical research and makes suggestions on how design engineers may improve the accuracy of their deflection computations.

DOI:

10.14359/10031


Document: 

SP133-16

Date: 

September 1, 1992

Author(s):

Howard H. M. Hwang and Hui-Mi Hsu

Publication:

Symposium Papers

Volume:

133

Abstract:

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.

DOI:

10.14359/3062


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


Document: 

SP133-12

Date: 

September 1, 1992

Author(s):

Dan M. Frangopol

Publication:

Symposium Papers

Volume:

133

Abstract:

A formulation is presented for extending structural system design concepts from safety and serviceability to damage tolerability. The assumptions necessary to implement damage tolerability concepts in structural system design are explained using both deterministic and probabilistic approaches. A particular emphasis is placed upon redundancy measures and their use in system damage-tolerant optimum design. Examples of solutions for optimum system design for safety, serviceability, and damage tolerability are presented.

DOI:

10.14359/3163


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