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Evaluation and Retrofit of Lightly Reinforced Concrete Buildings

Abstract
Objective and Approach
Accomplishments (Full Text)
Collaboration
Technical References
Publications
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Abstract

Gergely, P., Reinhorn, A., White, R., Kunnath, S., Evaluation and Retrofit of
Lightly Reinforced Concrete Buildings. Research Accomplishments, 1986-1994:
The National Center for Earthquake Engineering Research, pages 19-28. (Buffalo :
National Center for Earthquake Engineering Research, September 1994)

One of the major areas of research in the buildings project has been the evaluation of the performance and study of the rehabilitation of existing concrete buildings. Most of these structures were designed only for gravity loads, without any consideration of seismic forces. The seismic behavior of typical gravity-load designed (GLD) buildings has been studied through a coordinated program of full-scale component tests, reduced-scale shake table model tests, and analytical simulation. Guidelines have been developed and a monograph has been drafted to assist engineers in evaluating gravity-load designed buildings. The rehabilitation study has concentrated on simple techniques especially suited to regions of moderate seismicity.

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The objective of this research program is to evaluate the seismic performance of existing gravity-load designed concrete buildings and to study simple rehabilitation methods. The knowledge gained from the program is being synthesized to provide evaluation guidelines for practicing engineers.

To obtain information on the cyclic behavior of gravity-load designed concrete frame buildings which have no seismic details, a coordinated research program was carried out at several institutions. The research involved cyclic load tests of full-scale structural components, shake table tests of building models, and the development of analytical tools. The behavioral models developed in the experimental study were incorporated into the computer program IDARC, which allowed nonlinear dynamic analyses of typical buildings. A monograph has been written to summarize the research and to provide evaluation guidelines and methodologies for practicing engineers. In the rehabilitation study, several relatively simple ways of upgrading gravity-load designed buildings were examined.

This research task is part of NCEER's Building Project. Task numbers are: 86-3032,87-1005,88-1002,89-1001,90-1001, 91-3111, 91-3112, 91-3114, 91-3115, 92-3101,92-3102,92-3103,92-3104,93-3101 and 93-3102.

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Accomplishments

This coordinated research program has been directed at assessing the safety of lightly-reinforced, gravity-load designed concrete structures under earthquake forces. Prior to this work, no systematic investigation had been made on this large and important class of construction. The results have direct application to a significant improvement in the evaluation of existing structures, to the development of schemes for rehabilitating structures, and improvement of design requirements for new construction.

These types of buildings were not designed for seismic loading and contain such nonseismic details as low percentage of longitudinal steel in the columns and beams, lightly-confined column lapped splices just above the floor level, little or no transverse reinforcement in the beam-column joint, discontinuous positive beam reinforcing steel that terminates six inches into the joint, and construction joints above and below the beam-column joint.

This coordinated program, involving several institutions, relied on full-scale tests of beam-column assemblages, reduced-scale component tests, shake table tests of three building models, the development of analytical models which were incorporated into the computer program IDARC (Inelastic Damage Analysis of Reinforced Concrete Structures), parametric studies of the dynamic response of typical buildings, and development of simple rehabilitation techniques.

Several experimental facilities were upgraded to permit the various types of static and dynamic tests required in the research. A computer-controlled test facility was designed and built at Cornell University to test the full-scale cruciform specimens representing the beam-column connection region and portions of the beams and columns framing into the connection. A modern MTS loading system was constructed, including loading jacks, pumps, and fuel lines. A seven-foot shaking table was constructed with its loading system and data acquisition system. The existing large shaking table at the University at Buffalo was upgraded to make it one of the most versatile systems in North America. The data acquisition and other static loading systems were also significantly expanded.


Full-scale and Reduced-scale Component Tests

Figure 1
A typical specimen of an
interior joint region is tested at
the Cornell University facility.

Over 30 full-scale interior and exterior joint specimens were tested at Cornell University. A typical test is shown in figure 1 (Beres, et. al., 1992b). These specimens generally performed better than expected in terms of strength, ductility and energy absorption capacities. The shear strength capacities of interior and exterior joints are summarized in Figure 2 (Beres, et. al.,1992a) for the two types of joints and in comparison to the strength levels for well-designed joints.

Several 1:3 scale components of joints of beam-slab-column specimens were tested at the University at Buffalo. The specimens were identical to those constructed in a structural model of three stories that was subsequently tested on the shaking table. The tests of the original and retrofitted joints showed better deformation capacity than expected (Aycardi, et. al, 1992 and Choudhuri, et. al., 1992).

The full-scale component tests at Cornell and the reduced-scale component (joint assembly) tests at the University at Buffalo and at Cornell, assisted in the analytical idealization of the nonlinear response of these elements with poor details. This information was incorporated into the program IDARC and used to plan the shake table tests.


Shake Table Tests

Many shake table tests were performed on three reduced-scale three-story buildings at University at Buffalo and at Cornell. These models were subjected to a series of ground motions to study their dynamic response and to compare it with analytical predictions.

A typical set of results for the Taft 1952 earthquake, scaled to 0.20g maximum ground acceleration, is shown in table 1 (Bracci, et. al.,1992) for the 1/3-scale model tested at the University at Buffalo. Similar results were obtained in the shake-table tests of a 1/6 scale three-story building at Cornell. The model collapsed due to failure of the internal columns when the acceleration level was increased above about 0.35g.

Story Max. Story
Displacement
(in.)
Max Intr-
Story drift
(%)
Max. Story
Shear
(kips)
Max. Story
Load
(kips)
Peak Story
Acceleration
(g)
Third 1.32 0.54 5.6 5.6 0.20
Second 1.14 1.07 9.3 5.7 0.20
First 0.64 1.33 12.3(15.2%W) 7.8 0.25
Table 1. Maximum Response for Moderate Earthquake TFT_20

The shaking table tests of the 1:3 scale model showed deformations demand well below the deformation capacity of joints and of entire floors for moderate earthquakes, and near capacity for severe earthquakes. The analytical evaluation of the shaking table tests indicated that the model was tested near collapse (Bracci, et. al., 1992), with an almost complete mechanism similiar to the collapsed 1:6 scale model.


Nonlinear Dynamic Analyses

The IDARC computer program was used for static and dynamic nonlinear analyses of typical gravity-load designed buildings. The results indicate that many of these structures would not collapse in moderate earthquakes (up to about 0.2g maximum ground acceleration) because of their inherent flexibility and further reduction of stiffness caused by slip of the embedded beam bars. The periods of these structures are relatively long and the base shear relatively small as indicated in table 2, (Hoffman, et. al., 1992). The slip of the bottom bars reduces the maximum force that can be delivered to the columns. However, large displacements would cause extensive nonstructural damage. The maximum drifts were significantly lower for the Nahanni earthquake, which is considered to be an East-coast type motion, as shown in table 3 (Hoffman, et. al., 1992). Column shear failure is a possibility in buildings of moderate height.

Building
Type
Fundamental
Period
Maximum
Base Shear
Coefficient
3 Story 0.79 s 0.056
6 Story 1.15 s 0.037
9 Story 1.48 s 0.028
Table 2. Fundamental Periods and Base Shear Coefficients

Buildings on soft soils or those subjected to ground motions with low frequencies dominating could reach the collapse stage. Conversely, motions with strong energy in the high-frequency range, which may be typical for nearby motions in the East, do not excite these buildings to significant displacements.

Building
Type
Artificial
Earthquake
PGA = 0.15 g
Nahanni
PGA = 0.20 g
El Centro
PGA = 0.20 g
Taft
PGA = 0.20 g
3 Story: 0.53% 0.31% 1.16% 3.06%
6 Story: 0.95% 0.51% 2.67% 4.47%
9 Story: 0.63% 0.61% 1.17% 1.83%
Table 3. Maximum Inter-Story Drifts



Building with Flexible Floor Diaphragms

Figure 3
Analytical prediction of middle
frame base shear and comparison
with test result [1 kip = 4.448 kN].

One of the problems studied was the response of buildings with floor diaphragms which are flexible in their planes and/or respond inelastically during a strong earthquake. Shake table experiments were performed at the University at Buffalo on a three-story model and IDARC was modified to account for diaphragm flexibility and inelasticity using a simplified macromodel.

The building model had a plan aspect ratio of 1 to 3.3. It had five frames in the short direction; the two end frames had shear walls. During the elastic response, the three interior frames carried only 4.6% of the total shear. This share doubled after the first yielding of the middle of the slab. After extensive cracking and yielding of the slab, the interior frames carried over 20% of the shear. The maximum displacement of the center of the slab was 6.2 times the maximum end frame displacement, however, the increase of ductility demand on the interior frames was not great in this case. The analytical and experimental base shears in the center frame are compared in figure 3 (Reinhorn, et. al., 1991).

The experimental and analytical results showed that the customary assumption of rigid floors is not satisfactory for long narrow buildings, especially if L- or T-shaped in plan. If the floor slab experiences severe cracking or yielding, the response of the building can be altered significantly and the demand can increase substantially on some of the frames.


Nonductile Flat-plate Buildings

Four two-bay flat-plate subassemblies, containing details typically found in such buildings, common in the East Coast, were subjected to a series of tests. Under normal service gravity loads, flexural yielding developed in the negative moment regions of the slabs. However, under high gravity loads, punching limited the strength of the interior connections. The positive moment capacity of slabs at the connections was limited to the cracking strength. Similarly, high gravity loads reduced the maximum lateral drift to about 2% from a drift of 4.5% for normal vertical loads. The lack of bottom slab steel anchorage did not have much effect on response except on the punching strength.

It was found that although the lateral stiffness was reduced by about 80%, the connections were able to maintain about 80% of the lateral load through large drifts, unless high gravity loads caused punching failure. None of the exterior connections experienced punching failure.


Retrofit Studies

Several retrofit (rehabilitation) schemes were developed and evaluated to eliminate the weak-column mechanism, to reinforce the joints, or to reduce the flexibility due to the insufficient anchorage of bottom beam bars. Other retrofit schemes included the use of viscous or friction dampers.

Some of the columns of the three-story building model were retrofitted using prestressed jacketing and tested on a shaking table. This approach was successful in delaying the weak-column story mechanism and in shifting the failure to the beams at reduced story drift levels.

Local retrofit of internal and external joints using external steel plates to compensate for the lack of continuity of bottom beam bars was effective in supplying some positive moment capacity and large ductility. The plates attached to the outside faces of external joints prevented the spalling of the concrete and thus increased the capacity of the column lapped splices.

Supplemental damping using viscous fluids, friction, and viscoelastic devices were verified experimentally and analytically as retrofit solutions for damaged reinforced concrete structures. The additional damping proves to be beneficial in reducing the deformation (drift) demand in uniform wave earthquakes without reducing the shear force demand. However, this additional damping may not be as beneficial in earthquakes with large velocity pulses (shock type). Engineering solutions to such earthquakes may be feasible with more complex nonlinear devices. The investigation in this subject is still continuing analytically and experimentally.

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Christopher H. Conley
Peter Gergely
Richard N.White
Cornell University

Ahmad Durrani
Rice University

John Mander
Andrei Reinhorn
University at Buffalo

Nadar Panahshahi
Southern Illinois University

Sashi Kunnath
University of Central Florida

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Technical References

Aycardi, L.E., Reinhorn,A.M., and Mander,J.B.,"Seismic Resistance of Reinforced Concrete Frame Structures Designed only for Gravity Loads: Part II - Experimental Performance of Subassemblages," Technical Report NCEER-92-0028,National Center for Earthquake Engineering Research, University at Buffalo, December 1,1992.

Beres,A.,White, R.N., and Gergely, P.,"Seismic Behavior of Reinforced Concrete Frame Structures with Nonductile Details: Part I - Summary of Experimental Findings of Full Scale Beam-Column Joint Tests," Technical Report NCEER-92-0024, National Center for Earthquake Engineering Research. University at Buffalo, September 30, 1992.

Beres, A., El-Borgi, S., White, R.N., and Gergely, P., "Experimental Results of Repaired and Retrofitted Beam-Column Joint Tests in Lightly Reinforced Concrete Frame Buildings," Technical Report NCEER-92-0025, National Center for Earthquake Engineering Research, University at Buffalo, October 29, 1992.

Bracci, J.M., Reinhorn, A.M., and Mander, J.B., "Seismic Resistance of Reinforced Concrete Frame Structures Designed only for Gravity Loads: Part III - Experimental Performance and Analytical Study of a Structural Model," Technical Report NCEER-92-0029, National Center for Earthquake Engineering Research, University at Buffalo. December 1, 1992.

Choudhuri, D., Mander, J.B., and Reinhorn, A.M., "Evaluation of Seismic Retrofit of Reinforced Concrete Frame Structures: Part I - Experimental Performance of Retrofitted Subassemblies," Technical Report NCEER-92-0030, National Center for Earthquake Engineering Research, University at Buffalo. December 8, 1992.

Hoffmann, G.W., Kunnath, S.K., Reinhorn,A.M, .and Mander, J.B.,"Gravity-Load-Designed Reinforced Concrete Buildings: Seismic Evaluation of Existing Construction and Detailing Strategies for Improved Seismic Resistance," Technical Report NCEER-92-0016, National Center for Earthquake Engineering Research, University at Buffalo, July 15, 1992.

Reinhorn, A.M., Panahshahi, N., Kunnath, S.K., Lu, L.W., Huang,T.T., and Yu, K.,"Seismic Response of a 1:6 Scaled Model Structure with Flexible Floor Diaphragms," ACI Structural Journal, Vol.88, No.3, 1991, pp.315-324.

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Publications

Technical Reports

Aycardi, L.E., Reinhorn,A.M., and Mander,J.B.,"Seismic Resistance of Reinforced Concrete Frame Structures Designed only for Gravity Loads: Part II, Experimental Performance of Subassemblages," Technical Report NCEER-92-0028, National Center for Earthquake Engineering Research, University at Buffalo. December 1, 1992.

Beres, A., ElBorgi, S., White, R.N., and Gergely, P.,"Experimental Results of Repaired and Retrofitted Beam-Column Joint Tests in Lightly Reinforced Concrete Frame Buildings," Technical Report NCEER-92-0025, National Center for Earthquake Engineering Research, University at Buffalo, October 29. 1992.

Beres, A., ElBorgi, S., White, R.N., and Gergely, P.,"FullScale Tests of Retrofitted Beam-Column Joints in Lightly Reinforced Concrete Frame Buildings," Report 2 of 3, NIST Project on Seismic Strengthening Methodologies for Reinforced Concrete Frame Buildings, March 1992.

Beres, A.,White, R.N., and Gergely, P.,"Seismic Behavior of Reinforced Concrete Frame Structures with Nonductile Details: Part I-Summary of Experimental Findings of Full Scale Beam-Column Joint Tests," Technical Report NCEER-92-0024, National Center for Earthquake Engineering Research, University at Buffalo, September 30,1992.

Beres, A., White, R.N., and Gergely, P.,"Seismic Performance of Interior and Exterior Beam-to-Column Joints Related to Lightly Reinforced Concrete Frame Buildings, Detailed Experimental Results," Structural Engineering Report 92-7, School of Civil and Environmental Engineering, Cornell University, Ithaca, New York, November 1992.

Bracci,J.M., Reinhorn, A.M., and Mander, J.B.,"Evaluation of Seismic Retrofit of Reinforced Concrete Frame Structures: Part II, Experimental Performance and Analytical Study of a Retrofitted Structural Model," Technical Report NCEER-92-0031, National Center for Earthquake Engineering Research, University at Buffalo, December 8, 1992.

Bracci, J.M., Reinhorn, A.M., and Mander, J.B., "Seismic Resistance of Reinforced Concrete Frame Structures Designed only for Gravity Loads: Part III - Experimental Performance and Analytical Study of a Structural Model," Technical Report NCEER-92-0029, National Center for Earthquake Engineering Research, University at Buffalo, December 1, 1992.

Bracci, J.M., Reinhorn, A.M., and Mander,J.B.,"Seismic Resistance of Reinforced Concrete Frame Structures Designed Only for Gravity Loads: Part I, Design and Properties of a One-Third Scale Model Structure," Technical Report NCEER-92-0027, National Center for Earthquake Engineering Research, University at Buffalo, December 1, 1992.

Bracci,J.M., Reinhorn, A.M., Mander, J.B., and Kunnath, S.K., W,"Deterministic Model for Seismic Damage Evaluation of Reinforced Concrete Structures," Technical Report NCEER-89-0033. National Center for Earthquake Engineering Research, University at Buffalo, September 27, 1989.

Choudhuri, D., Mander, J.B., and Reinhorn, A.M., "Evaluation of Seismic Retrofit of Reinforced Concrete Frame Structures: Part I, Experimental Performance of Retrofitted Subassemblies," Technical Report NCEER-92-0030, National Center for Earthquake Engineering Research, University at Buffalo. December 8, 1992.

Corazao, M., and Durrani,AJ., "Repair and Strengthening of Beam-Column Connections Subjected to Earthquake Loading," Technical Report NCEER-89-0013, National Center for Earthquake Engineering Research, University at Buffalo, February 28, 1989.

El-Attar, A., White, R.N., and Gergely, P, "Shake Table Test of a 1/8 Scale-Three-Story Lightly Reinforced Concrete Building," Technical Report NCEER-91-0018, National Center for Earthquake Engineering Research, University at Buffalo, February 10, 1991.

El-Attar, A., White, R.N., and Gergely, P., "Shake Table Test of a 1/6 Scale Two-Story Lightly Reinforced Concrete Building," Technical Report NCEER-91-0017, National Center for Earthquake Engineering Research, University at Buffalo, February 30, 1991.

El-Borgi, S., Stone, W.C., White, R.N., and Gergely, P., "Analytical Study on Seismic Behavior of Lightly Reinforced Concrete Frame Buildings," Report 3 of 3, NIST Project on Seismic Strengthening Methodologies for Reinforced Concrete Frame Buildings, September 1992.

El-Borgi, S., White, R.N., and Gergely, P, "Analytical Models for Seismic Retrofit of Lightly-Reinforced Concrete Frame Buildings," Report 1 of 3, NIST Project on Seismic Strengthening Methodologies for Reinforced Concrete Frame Buildings, September 1991.

Hoffmann, G.W., Kunnath, S.K., Reinhorn,A.M, .and Mander, J.B.,"Gravity-Load-Designed Reinforced Concrete Buildings: Seismic Evaluation of Existing Construction and Detailing Strategies for Improved Seismic Resistance,"Technical Report NCEER-92-0016, National Center for Earthquake Engineering Research, University at Buffalo, July 15,1992.

Kunnath, S.K., and Reinhorn, A.M., "Inelastic Three-Dimensional Response Analysis of Reinforced Concrete Building Structures (IDARC-3D), Part I: Modeling," Technical Report NCEER-89-0011, National Center for Earthquake Engineering Research, University at Buffalo, January 29, 1989.

Park,YJ., Reinhorn, A.M., Kunnath, S.K.,"IDARC - Inelastic Damage Analysis of Reinforced Concrete Wall Frame Structures," Technical Report NCEER-87-0008, National Center for Earthquake Engineering Research, University at Buffalo, July 20, 1987.

Pessiki, S.P, Conley, C., Bond, T., Gergely, P., and White, R.N., "Reinforced Concrete Frame Component Testing Facility Design, Construction, Instrumentation, and Operation," Technical Report NCEER-88-0047, National Center for Earthquake Engineering Research, University at Buffalo, December 16, 1988.

Pessiki, S.P, Conley, C.H., Gergely, P., and White, R.N., "Seismic Behavior of Lightly-Reinforced Concrete Column and Beam-Column Joint Details," Technical Report NCEER-90-0014, National Center for Earthquake Engineering Research, University at Buffalo, August 22, 1990.

Reinhorn, A.M., Kunnath, S.K., and Panahshahi, N., "Modeling of R/C Building Structures with Flexible Floor Diaphragms (IDARC2)," Technical Report NCEER-88-0035, National Center for Earthquake Engineering Research, University at Buffalo, September 7,1988.

Reinhorn, A.M., Seidel, M.J., Kunnath, S.K., and Park,Y.J., "Damage Assessment of Reinforced Concrete Structures in the Eastern United States," Technical Report NCEER-88-0016, National Center for Earthquake Engineering Research, University at Buffalo, June 15, 1988.

Papers

"Analytical Modeling of Inelastic Seismic Response of R/C Structures," ASCE Journal of Structural Engineering, Vol.116, No.5, April 1990, pp. 996-1017.

Beres,A., Pessiki, S., White, R.N., and Gergely, P.,"Seismic Performance of Existing Reinforced Concrete Frames Designed Primarily for Gravity Loads," Proceedings, Sixth Canadian Conference on Earthquake Engineering, Toronto, June 1991.

Beres, A., Pessiki, S.P, White, R.N., and Gergely, P.,"Behavior of Existing Reinforced Concrete Frames Designed Primarily for Gravity Loads," Proceedings, International Meeting on Earthquake Protection of Buildings, Ancona, Italy, June 1991, pp. 75-86.

Beres,A., White, R.N., Gergely, P, Pessiki, S., and El-Attar, A., "Behavior of Existing, Non-Seismically Detailed Reinforced Concrete Frames," Proceedings,Tenth World Conference on Earthquake Engineering, Madrid, Spain, July 1992, pp.3359-3363

Bracci, J.M., Lobo, R.E, and Reinhorn, A.M., "Seismic Retro fit of Reinforced Concrete Structures Using Damping Devices," Proceedings, ATC-17-1 Seminar on Seismic Isolation, Passive Energy Dissipation, and Active Control, San Francisco, California, March 11-12, 1993, Vol.2, pp.569-580.

Bracci, J.M., Reinhorn, A.M., and Mander, J.B., "Seismic Resistance of Reinforced Concrete Frame Structures Designed for Gravity Loads: Performance of Structural System," ACI/ Structural Journal, January 1994.

Bracci, J.M., Reinhorn, A.M., and Mander, J.B.,"Seismic Retrofit of Reinforced Concrete Buildings Designed for Gravity Loads: Performance of Structural Models," ACI Structural Journal, January 1994.

El-Attar, A., White, R.N., Gergely, P., and Bond, T.K., "Shake Table Test of a 1/8 Scale Three-Story Reinforced Concrete Frame Building Designed Primarily for Gravity Loads," Proceedings, Sixth Canadian Conference on Earthquake Engineering, Toronto, June 1991, pp.639-646.

El-Attar, A., White, R.N., Gergely, P, and Conley, C.,"Shake Table Tests of a 1/6 Scale 2-story Lightly-Reinforced Concrete Building," Proceedings, Fourth U.S. National Conference on Earthquake Engineering, Palm Springs, California, May 1990.

El-Attar, A., White, R.N., Gergely, P., Reinhorn, A., Mander, J., and Kunnath, S.,"Lightly Reinforced Concrete Buildings Subjected to Earthquake Loads: Shake Table Tests on 1/8 and 1/3 Scale Building Models," 1991 EERI Annual Meeting Poster Session, Salt Lake City, February 1991.

El-Borgi, S., White, R.N., Gergely, P., and Beres, A.,"Evaluation and Analysis of Existing Lightly Reinforced Concrete Buildings," Proceedings, 1993 National Earthquake Conference, Memphis, Tennessee, May 1993.

Gergely, P., and White, R.N., "NCEER Overview and Interaction with Other Projects," Proceedings, ASCE Structures Congress, Baltimore, Maryland, May 1990.

Gergely, P., and White, R.N.,"The Evaluation of Existing Concrete Buildings in Moderate Seismic Zones," Proceedings, First Egyptian Conference on Earthquake Engineering, Hurghada, Egypt, December 1993, pp.305-315.

Kunnath, S.K., and Jenne, C., "Seismic Damage Assessment of Inelastic RC Structures," Proceedings, Fifth U.S. National Conference on Earthquake Engineering, Chicago, Illinois, 1994.

Kunnath, S.K., and Reinhorn, A.M., "Efficient Modeling Scheme for Transient Analysis of Inelastic RC Structures," Microcomputers in Civil Engineering, International Journal of Computer-Aided Civil and Infrastructure Engineering, December 1994.

Kunnath, S.K., and Reinhorn, A.M., "Inelastic Response of R/C Beam Columns Under Biaxial Excitations," Proceedings, Fourth U.S. National Conference on Earthquake Engineering, Palm Springs, California, Vol.2, May 1990, pp.471-479.

Kunnath, S.K., and Reinhorn, A.M.,"Model for Inelastic Biaxial Bending Interaction of R/C Beam-Columns," ACI Structural Journal, Vol.86, No.3, May-June 1990, pp.284-291.

Kunnath, S.K., Gasper, C., and Mehrain, M.,"Seismic Rehabilitation of RC Buildings," Proceedings, ACI Fall Convention, Minneapolis, Minnesota, 1993.

Kunnath, S.K., Hoffmann, G., Reinhorn, A.M., and Mander, J.B.,"Gravity Load Designed Reinforced Concrete Buildings, Part II: Evaluation of Detailing Enhancements," ACI Structural Journal, January 1994

Kunnath, S.K., Hoffmann, G., Reinhorn, A.M., and Mander, J.B.,"Gravity Load Designed Reinforced Concrete Buildings, Part I: Seismic Evaluation of Existing Construction," ACI Structural Journal, January 1994

Kunnath, S.K., Mander, J.B., and Reinhorn, A.M., "Seismic Response and Damageability of Gravity Load (NonSeismic) Designed Buildings," Proceedings, Ninth European Conference on Earthquake Engineering, Vol.9. Moscow, USSR October 1990, pp.323-332.

Kunnath, S.K., Panahshahi, N., and Reinhorn, A.M.,"Seismic Response of RC Buildings with Inelastic Floor Diaphragms, " Journal of Structural Engineering, Vol.117, No.4, 1991, pp.1218-1237.

Kunnath, S.K., Reinhorn, A.M., Abel, J.E, and Park, Y.J., "A Macromodel Approach to Practical Analysis of R/C Buildings under Seismic Excitation," in Computer Aided Analysis and Design of Concrete Structures, N. Bicanic and H. Mang (Eds.), Vol.2, Pineridge Press, Swansea U.K., 1990, pp.1155-1167.

Kunnath, S.K., Reinhorn, A.M., and Abel, J.E, "A Computational Tool for Evaluation of Seismic Performance of R/C Buildings," Computers and Structures, Vol.41, No.1, 1991, pp.157-171.

Kunnath, S.K., Reinhorn,A.M., and Park, YJ.,"MacroModeling of R/C Building Structures for Seismic Damage Analysis," Proceedings, Second East Asia Pacific Conference on Structural Engineering and Construction, Bangkok, Thailand, Vol.3, January 11-13, 1989, pp.79-84.

Kunnath, S.K., Reinhorn, A.M., and Park, Y.J., "Seismic Evaluation of R/C Frame Wall Buildings," ACI Concrete International Design & Construction, Special Issue, Vol.11, No.8, August 1989, pp. 57-61.

Lobo, R., Reinhorn, A.M., and Kunnath, S.K., "Inelastic Response of 3D R/C Structures to Multidimensional Seismic Input," Proceedings, Fifth U.S. National Conference on Earthquake Engineering, Chicago, Illinois, July 1994.

Lobo, R.F, Bracci, J.M., Shen, K., Reinhorn, A.M., and Soong, T.T.,"Inelastic Response of R/C Structures with Viscoelastic Braces," Earthquake Spectra, Vol.9, No.3, August 1993, pp.419-446.

Mander, J.B., Bracci, J.M., and Reinhorn, A.M.,"Seismic Retrofitting of Reinforced Concrete Frames Using Masonry," Proceedings, British Masonry Society, Vol.6, March 1994, pp.302-308.

Mander, J.B., Bracci, J.M., and Reinhorn, A.M., "Seismic Retrofitting of Reinforced Concrete Frames Using Masonry," Presented at the 3rd International Masonry Conference. London, British Masonry Journal, Vol.5, October 1992.

Mosalam, K.M., Gergely, P, and White, R.N.,"Three Dimensional Analysis of R/C Frame-Slab Building Systems," Proceedings, Fifth U.S. National Conference on Earthquake Engineering, Chicago, Illinois, July 1994.

Nagarajalah, S., and Reinhorn, A.M.,"Pseudo-force Method of Solution for Highly Nonlinear Systems," Proceedings, Eighth Conference on Computing and Civil Engineering, ASCE, Dallas, Texas, June 1992, pp.913-968.

Panahshahi, N., Kunnath, S.K., and Reinhorn, A.M.,"Inelastic Modeling of R/C Buildings with Flexible Floors" Proceedings, Fourth U.S. National Conference on Earthquake Engineering, Palm Springs, California, Vol.2, May 1990, pp.369-378.

Panahshahi, N., Reinhorn, A.M., and Kunnath, S.K.,"Earthquake Simulation Study of One-Six Scale Model R/C Building with Flexible Floor Diaphragms," Proceedings, Fifth U.S. National Conference on Earthquake Engineering, Chicago, Illinois, July 1994.

Park, Y.J., Reinhorn, A.M., and Kunnath, S.K.,"Seismic Damage Analysis of Reinforced Concrete Buildings," Proceedings, Ninth World Conference of Earthquake Engineering, Tokyo-Kyoto, Japan, Vol.VII, August 29, 1988, pp.211-216.

Pessiki, S., Conley, C., White, R.N., and Gergely, P,"Seismic Behavior of the Beam-Column Connection Region in Lightly-Reinforced Concrete Frame Structures," Proceedings, Fourth U.S. National Conference on Earthquake Engineering, Palm Springs, California, May 1990.

Pessiki, S., Conley, C., White, R.N., and Gergely, P.,"Seismic Resistance of the Beam-Column Connection Region in Lightly-Reinforced Concrete Frame Structures," Studie Richerche, Vol.11, pp.437-465, Milano, 1989.

Poland, C., Malley, J., Gergely, P., and White, R.N., "Seismic Evaluation of Buildings in the Eastern and Central United States " Proceedings, ASCE Structures Congress, San Francisco, May 1989.

Reinhorn, A.M., Bracci, J.M., and Mander, J.B.,"Seismic Retrofit of Gravity Load Designed Reinforced Concrete Buildings," Proceedings, 1993 U.S. National Conference Earthquake, Memphis, May 1993, pp.245-254.

Reinhorn, A.M., Kunnath, S.K., and Lobo, R., "3D Inelastic DynamicAnalysis of RC Structures," Proceedings, Eighth ASCE National Conference on Computing in Civil Engineering in Dallas, Texas. June 1992.

Reinhorn, A.M., Kunnath, S.K., and Mander,J.B.,"Seismic Design of Structures for Damage Control," in Nonlinear Seismic Analysis and Design of Reinforced Concrete Buildings, Fajfar and Krawinkler (Eds.), Elsevier Applied Science Publishers, U.K., 1992, pp.63-76.

Reinhorn, A.M., Kunnath, S.K., Bracci, J., and Mander, J.B., "Normalized Damage Index for Evaluation of Buildings," in Seismic Engineering: Research and Practice, C. A. Kircher and A K. Choora (Eds.), ASCE, New York, 1989, pp.507-516.

Reinhorn, A.M., Mander, J.B., and Kunnath, S.K., "Damage Based Design and Evaluation of Structural Systems Future Approach" in Developments in Seismic Design of Buildings in Israel, A. Scarlat (Ed.), Israeli Association of Civil Engineers/ Israeli Association of Earthquake Engineering, Tel Aviv, Israel, 1990, pp.3-12.

Reinhorn, A.M., Mander, J.B., Bracci, J., and Kunnath, S.K., "Simulation of Seismic Damage of RC Buildings in Eastern U.S.," Structural Safety & Reliability (ICOSSAR), A.H.S. Ang, M. Shinozuka and G.I. Schuller (Eds.), Vol.1, ASCE, New York, 1990, pp.407-414.

Reinhorn, A.M., Mander, J.B., Bracci, J.M., and Kunnath, S.K., "A Post-Earthquake Damage Evaluation Strategy for R/C Buildings," Proceedings Fourth U.S. National Conference on Earthquake Engineering, Palm Springs, California, Vol.2, May 1990, pp.1047-1056

Reinhorn, A.M., Panahshahi, N., Kunnath, S.K., Lu, L.W., Huang,T.T., and Yu, K., "Seismic Response of a 1:6 Scaled Model Structure with Flexible Floor Diaphragms," ACI Structural Journal, Vol.88, No.3, 1991, pp.315-324

Reinhorn, A. M., Valles, R., and Kunnath, S.K.,"Rapid Evaluation of Multistory Building Drift Under Lateral Loads," Proceedings, Ninth World Conference on Microcomputers in Civil Engineering, 1991, pp.120-124.

Seidel, M.I., Reinhorn, A.M., and Park, Y.J., "Seismsc Damageability Assessment of R/C Buildings in Eastern U.S.," ASCE Journal of Structural Engineering, Vol.115, No.9, Sept. 1989, pp.2184-2203.

"Seismic Resistance of Reinforced Concrete Frame Structures Designed Only for Gravity Loads: Experimental Performance of Subassemblages," ACI/Structural Journal, Vol.91, No. x, 1994, (in print).

Valles, R., Kunnath, S .K., and Reinhorn,A.M . ," Simplified Drift Evaluation of Wall-Frame Structures," Journal of Microcomputers in Civil Engineering,Vol.8, No.3, 1992, pp.233-246.

White, R.N., and Gergely, P,"Experiments on the Seismic Performance of Existing R/C Frames," Proceedings, Structures Congress ?2, ASCE, San Antonio, Texas, April 1992, pp.567-570.

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