International Concrete Abstracts Portal

ABOUT THE 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.

International Concrete Abstracts Portal

Showing 1-10 of 1188 Abstracts search results

Document: 

SP-339_01

Date: 

March 1, 2020

Author(s):

Xiaonian Duan, Andrea Soligon, Jeng Neo, and Anindya Dutta

Publication:

Symposium Papers

Volume:

339

Abstract:

The new Terminal 2 at the Tocumen International Airport in Panama, currently essentially completed, will increase the airport’s capacity to 25 million passengers per year. It has a doubly curved steel roof supported on reinforced concrete columns. The gravity force-resisting systems in the superstructure include long span precast and prestressed double tee decks, topped with cast-in-place concrete diaphragms and supported on a combination of unbonded post-tensioned girders and special reinforced concrete moment frame beams. The seismic force-resisting system includes special reinforced concrete moment frames and perimeter columns, special reinforced concrete shear walls and diaphragms, all detailed in accordance with ACI 318. Located in a region of moderately high seismic hazard, the building is classified as an essential facility and requires a non-conventional seismic design approach to maintain operational continuity and to protect life. Adopting the performance-based seismic design methodology and the capacity design principle, the structural engineering team designed an innovative reinforcement detail for developing ductile hinges at the top of the reinforced concrete columns to protect the structural steel roof which is designed to remain essentially elastic under MCE shaking. The structural engineering team’s design has been reviewed by internationally recognized experts and three independent peer review teams.


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_04

Date: 

March 1, 2020

Author(s):

Mark Sarkisian, Eric Long, and David Shook

Publication:

Symposium Papers

Volume:

339

Abstract:

Performance based seismic design (PBSD) has created new opportunities for enhanced performance, improved cost efficiencies, and increased reliability of tall buildings. More specifically, flexibility with initial design methods and the utilization of response history results for design, not just verification, have emerged. This paper explores four refined design methods made available by the employment PBSD to influence seismic performance and identify areas of importance. First is the initial proportioning of reinforcement to encourage plastic hinge behavior at specific locations. Second is the initial proportioning of wall thicknesses and reinforcements to encourage a capacity-based design approach for force-controlled actions. Third is the mapping of observed strain demands in shear walls to specific detailing types such as ordinary and special boundary zones. Fourth is an efficient envelope method for the design of foundations. Through these design methods, initial proportioning can be conducted in a more refined way and targeted detailing can result in cost savings. A case study of a recently designed high-rise residential building demonstrates that cost savings can be achieved with these methods.


Document: 

SP-339_12

Date: 

March 1, 2020

Author(s):

Burkhart Trost, Harald Schuler, and Bozidar Stojadinovic

Publication:

Symposium Papers

Volume:

339

Abstract:

Sliding failure of reinforced concrete shear walls was observed after the Chilean earthquakes in 1985 and 2010, during shaking table tests, and in many quasi-static cyclic shear walls tests. Sliding may occur along cold joints or flexural cracks that remain open due to permanent deformations induced during cyclic loading. If it occurs, sliding can significantly reduce the horizontal force resistance and change the deformation mechanism of reinforced concrete shear walls, and thereby markedly affect the seismic performance of shear wall buildings. This study provides the interaction diagrams intended to help reinforced concrete shear wall designers exclude the sliding failure mode. Regions where sliding, shear, and flexural failure modes are expected are delineated according to the shear wall shear span to length ratio, the axial force, the horizontal and vertical reinforcement ratios, and the concrete strength. These interaction diagrams are derived using a cyclic reinforced concrete wall response model that considers flexure, shear and sliding load-deformation relationships and the interaction between them. The inter-action diagram is used to develop design recommendations on how to avoid the sliding failure of reinforced concrete shear walls under earthquake loading.


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: 

SP-337_03

Date: 

January 23, 2020

Author(s):

Jeremiah D. Fasl and Carl J. Larosche

Publication:

Symposium Papers

Volume:

337

Abstract:

This paper will present the challenges and unique aspects associated with increasing the capacity of one of the container wharves at Barbour’s Cut Terminal to support new Ship-to-Shore (STS) container cranes with gage lengths of 100 ft. (30 m), which was an upgrade from the previous container cranes that featured 50-ft. (15 m) gage lengths. The design criteria included achieving an additional 50 years of service life from the existing elements and new elements; therefore, the assessment results and techniques used for service life modeling will be discussed. In the new structural elements, service life modeling was used to determine the necessary concrete mixture characteristics, including use of fly ash and corrosion-resistant reinforcement, to achieve the required service life.

This paper will also discuss the design approach, including the use of springs to represent the soil-structure interaction, for determining the demands on the various components. In addition, the interaction between the new structure and existing structure and the resulting torsion will be discussed. Finally, various lessons learned from using strut-and-tie modeling, including the relative stiffness of the chord elements and need for three-dimensional modeling, will be summarized.


Document: 

SP-337_02

Date: 

January 23, 2020

Author(s):

Widianto; Jameel Khalifa; Kåre O. Hæreid; Kjell Tore Fosså; Anton Gjørven

Publication:

Symposium Papers

Volume:

337

Abstract:

The Hebron platform is the latest major offshore integrated oil drilling and production platform supported by a concrete gravity-based-structure (GBS). It was successfully installed in the Grand Banks (offshore Newfoundland) in June 2017. The design of the platform was challenged by arctic-like and extreme metocean conditions. This paper presents development of extreme loads on the GBS such as 10,000-year iceberg impact and wave loads. It also describes novel design and construction techniques used, which resulted in a capitalefficient platform.

From an analysis and design perspective, in addition to linear-elastic finite element analysis typically used in design of offshore concrete GBS, the innovative use of non-linear finite element analysis (NLFEA) technique to calculate internal forces is presented. Such analyses more accurately capture the structural behavior and result in more realistic internal forces. In addition, a new crack-width calculation method accounting for the effect of a significant number of layers of transverse reinforcement was implemented. Also, a novel method to assess the complex interactions between solid ballast, embedded pipes, and concrete structures was applied.

From a construction perspective, the use of slipforming panels that are taller than those used in past GBSs and a system to allow slipforming of the shaft wall with a complex geometry and curvature, that is much larger than that employed in the past GBS, are presented. A novel method to minimize the risk of concrete adhering to slipforming panels by cooling the panels with cold water is presented. An innovative method to ensure that highstrength grout completely filled the space underneath one of the largest Topsides footings is discussed. Full-scale constructability tests of various complex GBS components, which provided invaluable information for design, increased execution certainty, and improved construction safety, is presented.


Document: 

SP-336_07

Date: 

December 11, 2019

Author(s):

David Darwin, Rouzbeh Khajehdehi, Muzai Feng, James Lafikes, Eman Ibrahim, Matthew O’Reilly

Publication:

Symposium Papers

Volume:

336

Abstract:

The goal of this study was to implement cost-effective techniques for improving bridge deck service life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the creation of Low-Cracking High-Performance Concrete (LC-HPC) specifications that minimize cracking through the use of low slump, low paste content, moderate compressive strength, concrete temperature control, good consolidation, minimum finishing, and extended curing. This paper documents the performance of 17 decks constructed with LC-HPC specifications and 13 matching control bridge decks based on crack surveys. The LCHPC bridge decks exhibit less cracking than the matching control decks in the vast majority of cases. Only two LCHPC bridge decks have higher overall crack densities than their control decks, which are the two best performing control decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. The results of this study demonstrate the positive effects of reduced cement paste contents, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, the use of good consolidation, minimizing finishing operations, and application of curing shortly after finishing and for an extended time on minimizing cracking in bridge decks.


Document: 

SP-333_08

Date: 

October 1, 2019

Author(s):

Needa Lingga, Yasir Saeed, Anas Yosefani, and Franz Rad

Publication:

Symposium Papers

Volume:

333

Abstract:

This research focused on concrete beams with voids simulating beams with fully corroded steel that were repaired with CFRP laminates. The experimental program included testing five, approximately one-third-scaled simply supported rectangular concrete beams. In three beams, the oiled steel rebars for flexure and shear were safely pulled out of the formwork after the concrete had cured for six hours, leaving voids. This technique was used to represent an extreme case of corrosion, albeit non-realistic, that is even worse than being exposed to the most corrosive environment. The aim was to investigate the extent of improvement by CFRP to flexural and shear capacity of beams that contain fully corroded steel bars, simulated by voids. The first specimen was with voids representing completely deteriorated steel. The second was a plain concrete beam without voids. The third beam was a typical code-designed reinforced concrete (RC) beam, that represented the “original undeteriorated” beam. The two remaining deteriorated beams were repaired by externally bonding one and two layers of CFRP. Load carrying capacity, deflection, and ductility were measured and compared. The novel results of this investigation were that test results showed that one layer of CFRP increased the load capacity to slightly higher than the RC beam, and two layers of CFRP increased it by a factor of two. Finally, a computer model was created to estimate the performance of the tested beams and to carry out a parametric study to investigate the effects of CFRP longitudinal reinforcement ratio and CFRP transverse confinement ratio on the flexural performance of CFRP-repaired concrete beams. The predicted contribution of CFRP to flexure and shear capacities was in good agreement with test results.


Document: 

SP-333_06

Date: 

October 1, 2019

Author(s):

Marco Rossini, Saverio Spadea, Antonio Nanni

Publication:

Symposium Papers

Volume:

333

Abstract:

Employment of corrosion-resistant reinforcement represents a widely-recognized effective strategy to ensure the long-term durability of reinforced concrete (RC) and prestressed concrete (PC) structures. Fiber-reinforced polymer (FRP) composites have proved to be a reliable non-metallic solution, able to ensure both the required mechanical performance and corrosion resistance. FRP-RC infrastructural applications are currently spreading; conversely, FRP-PC bridges are still considered state of the art prototypes. Many are the conceptual and practical challenges accompanying this innovative technology: brittleness of FRP reinforcement, the likelihood of tension-controlled failure, limitations on the initial pull force, limitations on the sustained load that the member can carry, and service requirements that may control the design. Reports published by ACI committee 440 do not yet address FRP-RC/PC provisions in a consistent way. Discrepancies exist on how ACI 440.1R and ACI 440.4R approach FRP-RC/PC design, having the latter not being updated since the first generation of FRP regulations. This paper deals with the philosophy behind the design of the precast Carbon FRP-PC/Basalt FRP-RC double-tee girders and the auxiliary Basalt FRP-RC/Glass FRP-RC members that constitute the structure of a recently built pedestrian bridge. This study is an attempt to address the challenges still preventing the wide acceptance of CFRP in prestress applications and to unify the design approach for FRP-RC/PC structures. This successful case-study validates the proposed rationale and supports a slight relaxation of the design limits in terms of the initial pull force.


12345...>>

Results Per Page 




Please enter this 5 digit unlock code on the web page.