Sri Sritharan

Bio: Sri Sritharan is an academic researcher from Iowa State University. The author has contributed to research in topics: Precast concrete & Seismic analysis. The author has an hindex of 26, co-authored 187 publications receiving 3482 citations. Previous affiliations of Sri Sritharan include GNS Science & British University in Egypt.

Preliminary results and conclusions from the PRESSS five-story precast concrete test Building

Abstract: A large-scale five-story precast concrete building constructed to 60 percent scale was tested under simulated seismic loading as the culmination of the 10-year PRESSS (Precast Seismic Structural Systems) research program. The building comprised four different ductile structural frame systems in one direction of response and a jointed structural wall system in the orthogonal direction. The test structure was subjected to seismic input levels equivalent to at least 50 percent higher than those required for UBC (Uniform Building Code) Seismic Zone 4. The behavior of the structure was extremely satisfactory, with only minimal damage in the shear wall direction, and no significant strength loss in the frame direction, despite being taken to drift levels up to 4.5 percent, more than 100 percent higher than the design drift level. The test validated the Displacement-Based Design (DBD) approach used to determine the required strength and confirmed the low damage and low residual drift expected of the building.

Modeling of Strain Penetration Effects in Fiber-Based Analysis of Reinforced Concrete Structures

Abstract: Focusing on the member end rotation due to strain penetration along reinforcing bars fully anchored in footings and bridge joints, this paper introduces a hysteretic model for the reinforcing bar stress versus slip response. This model can be integrated into fiber-based analysis of concrete structures using a zero-length section element. The authors demonstrate the ability of the proposed hysteretic model to capture the strain penetration effects by simulating the measured global and local responses of two concrete columns and a bridge T-joint system. Findings show that the analysis of concrete structures will appreciably underestimate the local response parameters that are used to quantify structural damage unless the strain penetration effects are satisfactorily modeled.

Seismic-Resistant Precast Concrete Structures: State of the Art

Abstract: Precast concrete facilitates a construction method using durable and rapidly erectable prefabricated members to create cost-effective and high-quality structures. In this method, the conne...

An Overview of the PRESSS Five-Story Precast Test Building

Abstract: At the culmination of the PRESSS (Precast Seismic Structural Systems) research program, a 60 percent scale five-story precast/prestressed concrete building will be tested under simulated seismic loading. This paper describes the prototype buildings used for design and the structural features of the test building. The buildings were designed using the direct displacement based approach, which is able to take advantage of the unique properties of precast/prestressed concrete using dry jointed construction. The test building incorporates four different seismic frame systems in one direction, and a jointed shear wall system in the orthogonal direction. Pretopped double tees are used on three floors, while the other two floors are constructed using topped hollow-core slabs. A major objective of the test program is to develop design guidelines for precast/prestressed concrete seismic systems that are appropriate for use in various seismic zones. These design guidelines can then be incorporated into the appropriate building codes.

Analytical modelling of the seismic behaviour of precast concrete frames designed with ductile connections

Abstract: Pure precast beam-column systems incorporate unbonded reinforced at the critical sections, causing strain incompatibility between steel and concrete. As a result, classical section analysis method,...

"building code requirements for structural concrete (aci 318-11) and commentary"

Abstract: The “Building Code Requirements for Structural Concrete” (“Code”) covers the materials, design, and construction of structural concrete used in buildings and where applicable in nonbuilding structures. The Code also covers the strength evaluation of existing concrete structures. Among the subjects covered are: contract documents; inspection; materials; durability requirements; concrete quality, mixing, and placing; formwork; embedded pipes; construction joints; reinforcement details; analysis and design; strength and serviceability; flexural and axial loads; shear and torsion; development and splices of reinforcement; slab systems; walls; footings; precast concrete; composite flexural members; prestressed concrete; shells and folded plate members; strength evaluation of existing structures; provisions for seismic design; structural plain concrete; strut-and-tie modeling in Appendix A; alternative design provisions in Appendix B; alternative load and strength reduction factors in Appendix C; and anchoring to concrete in Appendix D. The quality and testing of materials used in construction are covered by reference to the appropriate ASTM standard specifications. Welding of reinforcement is covered by reference to the appropriate American Welding Society (AWS) standard. Uses of the Code include adoption by reference in general building codes, and earlier editions have been widely used in this manner. The Code is written in a format that allows such reference without change to its language. Therefore, background details or suggestions for carrying out the requirements or intent of the Code portion cannot be included. The Commentary is provided for this purpose. Some of the considerations of the committee in developing the Code portion are discussed within the Commentary, with emphasis given to the explanation of new or revised provisions. Much of the research data referenced in preparing the Code is cited for the user desiring to study individual questions in greater detail. Other documents that provide suggestions for carrying out the requirements of the Code are also cited.

Properties Of Concrete

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Preliminary results and conclusions from the PRESSS five-story precast concrete test Building

Abstract: A large-scale five-story precast concrete building constructed to 60 percent scale was tested under simulated seismic loading as the culmination of the 10-year PRESSS (Precast Seismic Structural Systems) research program. The building comprised four different ductile structural frame systems in one direction of response and a jointed structural wall system in the orthogonal direction. The test structure was subjected to seismic input levels equivalent to at least 50 percent higher than those required for UBC (Uniform Building Code) Seismic Zone 4. The behavior of the structure was extremely satisfactory, with only minimal damage in the shear wall direction, and no significant strength loss in the frame direction, despite being taken to drift levels up to 4.5 percent, more than 100 percent higher than the design drift level. The test validated the Displacement-Based Design (DBD) approach used to determine the required strength and confirmed the low damage and low residual drift expected of the building.

Self-Centering Energy Dissipative Bracing System for the Seismic Resistance of Structures: Development and Validation

Abstract: Buildings designed according to modern seismic codes are expected to develop a controlled ductile inelastic response during major earthquakes, implying extensive structural damage after a design level earthquake, along with possibly substantial residual deformations. To address this drawback of traditional yielding systems, a new bracing system that can undergo large axial deformations without structural damage while providing stable energy dissipation capacity and a restoring force has recently been developed. The proposed bracing member exhibits a repeatable flag-shaped hysteretic response with full recentering capabilities, therefore eliminating residual deformations. The mechanics of this new system are first explained, the equations governing its design and response are outlined, and one embodiment of the system, which combines a friction dissipative mechanism and Aramid tensioning elements, is further studied. Results from component tests, full-scale (reduced length) quasi-static axial tests, and quasi-static and dynamic seismic tests on a full-scale frame system are presented. Experimental results confirm the expected self-centering behavior of the self-centering energy dissipative (SCED) bracing system within the target design drift. Results also confirm the validity of the design and behavior equations that were developed. It is concluded that the proposed SCED concept can represent a viable alternative to current braced frame systems because of its attractive self-centering property and because the simplicity of the system allows it to be scaled to any desired strength level.

Posttensioned Energy Dissipating Connections for Moment-Resisting Steel Frames

Abstract: The seismic performance of a posttensioned energy dissipating (PTED) connection for steel frames is investigated analytically and experimentally. The PTED connection incorporates posttensioned high-strength bars to provide a self-centering response along with energy dissipating bars that are able to yield in axial tension and compression. The analytical study involves the development of an equivalent iterative sectional analysis procedure to predict the moment-rotation relationship of the PTED connection. Based on this analytical model, a simple design procedure for PTED connections is described. In the experimental study, a cyclic component test was performed on two energy dissipating bars and a cyclic test was conducted on a large-scale exterior beam-to-column PTED connection. The results of the tests show that the PTED test specimen was able to undergo large inelastic deformations without any damage in the beam or column and without residual drift. The proposed analytical model and design procedure wer...