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International Concrete Abstracts Portal

Showing 1-5 of 18 Abstracts search results

Document: 

SP162-04

Date: 

August 1, 1996

Author(s):

A. E. Aktan and D. N. Farhey

Publication:

Symposium Papers

Volume:

162

Abstract:

Presents nondestructive and destructive dynamic field testing and structural identification studies on actual constructed facilities. The specimens discussed here include a 27-story reinforced concrete (RC) flat-slab building, an RC slab bridge, two 80-year-old steel truss bridges, and three RC slab on steel girder bridges of various ages. The seismic vulnerability of the mid-rise building was evaluated and the test bridges rated by code procedures as well as by field-calibrated comprehensive 3-D FE models developed by structural identification. Experimentally measured and analytically simulated modal flexibilities of the bridges were correlated with deflections obtained under proof-load-level truck-load tests. The rating factors obtained by filed- calibrated models exceeded the corresponding operating rating factors by two and a half to four times for all of the test bridges. These studies revealed our capabilities for evaluating vulnerability or reliability of different classes of facilities. The bridge rating efforts helped to identify and conceptualize a number of unresolved important issues that influence bridge rating and management. Serviceability aspects that emerged as critical were studied through the relative contributions of different mechanisms to bridge deflections.

DOI:

10.14359/1424


Document: 

SP162-10

Date: 

August 1, 1996

Author(s):

D. G. Morrison

Publication:

Symposium Papers

Volume:

162

Abstract:

The design of deepwater bottom-founded towers (300 to 1000 m) requires a good understanding of the nature of the design environment, the structural response, design force levels, and practical member sizing. The novel design tools described in this paper included the "Designer Wave" and the "Quickwave" methods. The "Designer Wave" is a practical short portion of random wave simulation that captures enough of the structural response (and shear and moment envelopes) for design purposes. The "Quickwave" method achieves reasonably accurate design forces and member sizes without using time consuming random wave runs and full 3-D structural models. The Designer Wave is essential for the occasional calibration of the Quickwave results. Many design iterations are relatively easy with the Quickwave, so much so that it was extensively used to derive a new deepwater compliant tower concept. The new tower configuration resulted in breakthrough savings in weight and costs relative to existing solutions.

DOI:

10.14359/1514


Document: 

SP162-05

Date: 

August 1, 1996

Author(s):

M. S. Saiidi, N. Wehbe, S. Acharya, and D. Sanders

Publication:

Symposium Papers

Volume:

162

Abstract:

Presents a review of (1) previous experimental studies on the earthquake response of square reinforced concrete columns and a discussion of their applicability to bridge columns in areas of moderate and high seismic risk; (2) confinement steel design for rectangular columns based on different codes and methods and an example column to compare these codes; and (3) two concrete confinement models in relationship to their application in estimating a range of displacement ductility for square columns, rectangular columns, and pier walls. The results of part (1) showed that previous tests on square columns are mostly under relatively large axial stresses which represent the state of building columns and that the data are generally aimed at areas of high seismic risk. Part (2) showed a considerable variation among different codes and methods in terms of the amount of lateral reinforcement and the parameters considered in design. The results of part (3) indicated that measured displacement ductilities were generally within a range calculated using the two confinement models selected in this study.

DOI:

10.14359/1425


Document: 

SP162-14

Date: 

August 1, 1996

Author(s):

A. Shibata, N. Inoui, and N. Hori

Publication:

Symposium Papers

Volume:

162

Abstract:

In the earthquake-resistant design of reinforced concrete (RC) buildings, it is necessary to evaluate inelastic behavior and damage of structures both by maximum displacement and by total energy dissipation. In this study, damage assessment of RC structures is carried out based on energy response. Damaging potential of earthquakes to structures is estimated by total input energy; damage of structures is estimated by the damage index taking account of both maximum response and cumulative damage. From the results of parametric inelastic response analyses using simulated earthquakes, it is considered that total input energy depends primarily on earthquake property. The damage parameter proposed by Fajfar, which relates ductility factor to dissipated hysteretic, seems to be relatively stable in many cases. The damage parameter is found useful to represent earthquake response pattern of structures. Using the damage parameter and the damage index, a procedure is presented to find yield force and corresponding ductility factor for given value of damage index. This study shows a possibility of a design concept of RC buildings considering displacement and energy limits.

DOI:

10.14359/1517


Document: 

SP162-06

Date: 

August 1, 1996

Author(s):

J. F. Bonacci and J. K. Wight

Publication:

Symposium Papers

Volume:

162

Abstract:

Members of earthquake-resisting reinforced concrete frames--such as beams, columns, joints, and anchorages--are designed on the basis of force demands. Detailing requirements are established from collected experimental observations of measures which are most effective in maximizing overall cyclic toughness of frame assemblies. In this paper, a displacement-based approach to evaluating detailing requirements for frame elements is presented. Expressions are derived for the participation of beams, columns, joints, and anchorages in overall story drift. Simple element models are presented for beam-column joints and anchorages; guidelines for conventional sectional analysis of beams and columns are given. With an assessment of the local demand in each element type and mechanical models of element behavior, it is demonstrated that member variables normally considered as part of detailing can be accounted for in a quantitative supply vs. demand fashion. A case study is made for an example in the ACI Committee 352 Recommendations to illustrate how a displacement-based frame evaluation is carried out and to provide a reference point for comparison with an existing design approach for beam-column joints.

DOI:

10.14359/1426


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