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Showing 1-5 of 14 Abstracts search results

Document: 

SP-339_05

Date: 

March 1, 2020

Author(s):

Sugeng Wijanto, Nelson M. Angel, José I. Restrepo, and Joel P. Conte

Publication:

Symposium Papers

Volume:

339

Abstract:

The rapid development of tall building construction has taken place in Indonesia over the last decade, especially in its capital, Jakarta. Reinforced concrete has been the preferred material of choice used for these buildings because it is economical and is easily handled by local contractors. Along with this rapid development, the Indonesian codes for structural design practices have experienced major changes, following the latest development of USA building design codes and performance-based design guidelines, especially those related to seismic design. This paper describes the latest seismic code in Indonesia and presents the state-of-the-practice for the design of tall buildings there. It also discusses the use of performance-based seismic design as an alternative method of design, considering the risk-targeted maximum and service earthquakes, in the structural design of a tall residential tower in Jakarta.


Document: 

SP-339_13

Date: 

March 1, 2020

Author(s):

Giulio Leon Flores, Reza V. Farahani, Hussien Abdel Baky, and Paul C. Rizzo

Publication:

Symposium Papers

Volume:

339

Abstract:

This paper presents the structural testing of four full-scale reinforced concrete beam-column connections, extracted from reinforced concrete buildings that suffered minor damage from the Canterbury Earthquakes in New Zealand. Two connections are extracted from a moment frame comprising the secondary seismic-resisting system of a concrete building; two are extracted from moment frames of the primary seismic-resisting systems of a precast concrete building. The seismic performance of the connections is evaluated from the test results and compared to recommendations in ASCE 41 (2013) for the evaluation of existing buildings. Due to the size of the specimens, the tests were stopped when the actuator reached its maximum stroke, at interstory drifts between 2.5% and 3. The cast-in-place connections showed moderate damage after the tests, at ductility levels above 2.9, and their initial lateral stiffness was approximately 80% of the lateral stiffness of numerical models representing the undamaged state. The precast connections exhibited extensive damage along the construction joint between the precast beams and the cast-in-place beam-column joint, at ductility levels above 3.4. The plastic mechanism was governed by sliding shear of the precast beams, which caused severe stiffness deterioration at the end of the tests. The measured stiffness in this case was approximately half of the stiffness predicted by numerical models in which nonlinearity is considered in the form of flexural plastic hinges only. This unexpected behavior is attributed to the low quantity of reinforcing steel crossing the construction joint, and presumably earthquake damage.


Document: 

SP-339_11

Date: 

March 1, 2020

Author(s):

Laura N. Lowes, Dawn E. Lehman, and Carson Baker

Publication:

Symposium Papers

Volume:

339

Abstract:

The PERFORM-3D software package is used commonly in engineering practice to conduct nonlinear dynamic analyses of reinforced concrete walled buildings to their seismic response. However, few studies have evaluated or improved on common modeling approaches for structural concrete walls. The research presented here was conducted to establish best practices for modeling the full nonlinear response of walls exhibiting common flexural failure modes. First, an experimental data set consisting of eight planar concrete walls was collected; these walls were spanned a range of length-to-thickness ratios, shear stress demands, axial load ratios, and longitudinal reinforcement configurations. For each wall specimen, a reference numerical model was created using typical modeling methods as proposed by Powell. Comparison of simulated and measured cyclic response histories show that typical modeling techniques result in relatively inaccurate simulation of cyclic response and very inaccurate simulation of drift capacity. To improve the model accuracy, experimental data were used to determine appropriate values for the steel and concrete material model cyclic response parameters. Experimental data and mathematical definitions for the concrete compressive energy were used to develop recommendations for defining concrete post-peak stress-strain response to achieve accurate, mesh-independent simulation of drift capacity. Finally, recommendations for the minimum number of elements were examined. Comparison of simulated and measured cyclic response histories show that the new modeling recommendation result in accurate, mesh independent simulation of cyclic response, including drift capacity. Future work will evaluate the proposed modeling approach for asymmetric and flanged walls.


Document: 

SP-339_10

Date: 

March 1, 2020

Author(s):

John S. Ma

Publication:

Symposium Papers

Volume:

339

Abstract:

The U.S. Nuclear Regulatory Commission (NRC) defines seismic Category 1 structures as the structures (buildings) that should be designed and built to withstand the maximum potential earthquake stresses for the particular region where a nuclear plant is sited. Seismic Category 1 structures have been designed for ground-shaking intensity associated with a safe-shutdown earthquake (SSE) – the intensity of the ground motion that will trigger the process of automatic shutdown of the reactor in operation. The SSE generates floor response spectra at different floor elevations in a building, and these spectra and their associated forces are used for the design of piping and piping anchors and equipment and equipment anchors at their floor locations. The NRC policy requires that the seismic Category 1 structures whose collapse could cause early or/and large release of radioactive materials into the atmosphere to be analyzed/designed for “no collapse” during the ground-shaking intensity of a review-level earthquake (RLE), which is 1.67 times that of an SSE. Most seismic Category 1 concrete structures, such as containment and shield buildings (curved cylindrical wall; see Figs. 1 and 2 in the next section) and containment internal structures (straight wall; see Fig. 1), use walls to resist earthquakes. This paper presents guidelines for the performance-based seismic design for these wall-typed structures that could meet the NRC policy. The method consists of (1) proportioning wall thickness based on shear stress of 6√fc’ (0.5√fc’ megapascals (MPa)) generated by SSE ground motions, (2) limiting vertical compressive stress in walls to less than 0.35 fc’, (3) providing minimum percentage of reinforcement of 1.0 percent to prevent steel reinforcing bar fracture, (4) subjecting the building design to nonlinear dynamic response analyses under RLE ground motions, (5) identifying any members and their connections in the building that have failed or collapsed during the RLE ground motions, (6) increasing reinforcement or wall thickness, or both, to provide additional strength or/and ductility for the failed or collapsed members and their connections, and (7) resubjecting the revised building design to the nonlinear dynamic response analyses as stated in step (4) until no collapse of the building and its members and their connections. This performance-based seismic design method is a direct, transparent, and scientific answer to whether these important seismic Category 1 structures meet the NRC’s policy that they will not collapse during the RLE ground motions. Examples of using the nonlinear dynamic response analyses are cited and described. Guidelines for the performance-based seismic design of seismic Category 1 concrete Structures are listed at the end of this paper.


Document: 

SP339

Date: 

March 1, 2020

Author(s):

Jeff Dragovich, Mary Beth Hueste, Brian Kehoe, and Insung Kim

Publication:

Symposium Papers

Volume:

339

Abstract:

Performance-Based Seismic Design (PBSD) of reinforced concrete buildings has rapidly become a widely used alternative to the prescriptive requirements of building code requirements for seismic design. The use of PBSD for new construction is expanding, as evidenced by the design guidelines that are available and the stock of building projects completed using this approach. In support of this, the mission of ACI Committee 374, Performance-Based Seismic Design of Concrete Buildings, is to “Develop and report information on performance-based seismic analysis and design of concrete buildings.” During the ACI Concrete Convention, October 15-19, 2017, in Anaheim, CA, Committee 374 sponsored three technical sessions titled “Performance-Based Seismic Design of Concrete Buildings: State of the Practice.” The sessions presented the state of practice for the PBSD of reinforced concrete buildings. These presentations brought together the implementation of PBSD through state-of-the-art project examples, analysis observations, design guidelines, and research that supports PBSD. This special publication reflects the presentations in Anaheim. Consistent with the presentation order at the special sessions in Anaheim, the papers in this special publication are ordered in four broad categories: state-of-the-art project examples (papers 1-5), lateral system demands (papers 6-8), design guidelines (papers 9-10), and research and observed behavior (papers 11-13). On behalf of Committee 374, we wish to thank each of the authors for sharing their experience and expertise with the session attendees and for their contributions to this special publication.


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