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International Concrete Abstracts Portal

Showing 1-5 of 142 Abstracts search results

Document: 

SP-345_16

Date: 

February 1, 2021

Author(s):

Gianmarco de Felice, Stefano De Santis, and Pietro Meriggi

Publication:

Symposium Papers

Volume:

345

Abstract:

In 2017, the Rilem Technical Committee 250-CSM coordinated a Round Robin initiative, in which 19 research institutions tested 28 Fabric Reinforced Cementitious Matrix (FRCM) composites, with the support of 11 industrial partners. Two years after the publication of the first papers on the results of this wide investigation, it is still worth further analysing its outcomes to highlight the fundamental properties of mortar-based reinforcements and give an overview of the various available fabrics and matrices, which are currently used in structural rehabilitation activities. Equally, a better understanding still needs to be gained on the causes of the variability observed in test results. These include the quasibrittle behaviour of the inorganic matrix and its sensitivity to manufacturing, curing and handling. Test implementation, such as gripping method and measuring techniques, also plays a crucial role in the reliability and repeatability of experimental outcomes.


Document: 

SP-345_12

Date: 

February 1, 2021

Author(s):

Xingxing Zou, Chris Moore, and Lesley H. Sneed

Publication:

Symposium Papers

Volume:

345

Abstract:

Externally bonded (EB) steel reinforced grout (SRG) composites have the potential to improve the flexural and shear performance of existing concrete and masonry structural members. However, one of the most commonly observed failure modes of SRG-strengthened structures is due to composite debonding, which reduces composite action and limits the SRG contribution to the member load-carrying capacity. This study investigated an endanchorage system for SRG strips bonded to a concrete substrate. The end anchorage was achieved by embedding the ends of the steel cords into the substrate. Nineteen single-lap direct shear specimens with varying composite bonded lengths and anchor binder materials were tested to study the effectiveness of the end-anchorage on the bond performance. For specimens with relatively long bonded length, the end-anchorage slightly improved the performance in terms of peak load achieved before detachment of the bonded region. Anchored specimens with long bonded length showed notable post-detachment behavior. Anchored specimens with epoxy resin achieved load levels significantly higher than the peak load before composite detachment occurred. For specimens with relatively short bonded length, the end-anchorage provided a notable increase in peak load and global slip at composite detachment. A generic load response was proposed for SRG-concrete joints with end anchors.


Document: 

SP341

Date: 

July 17, 2020

Publication:

Symposium Papers

Volume:

341

Abstract:

ACI Committees 441 – Reinforced Concrete Columns and 341A – Earthquake-Resistant Concrete Bridge Columns, Mohamed A. ElGawady Columns are crucial structural elements in buildings and bridges. This Special Publication of the American Concrete Institute Committees 441 (Reinforced Concrete Columns) and 341A (Earthquake-Resistant Concrete Bridge Columns) presents the state-of-the-art on the structural performance of innovative bridge columns. The performance of columns incorporating high-performance materials such as ultra-high-performance concrete (UHPC), engineered cementitious composite (ECC), high-strength concrete, high-strength steel, and shape memory alloys is presented in this document. These materials are used in combination with conventional or advanced construction systems, such as using grouted rebar couplers, multi-hinge, and cross spirals. Such a combination improves the resiliency of reinforced concrete columns against natural and man-made disasters such as earthquakes and blast.


Document: 

SP-341-09

Date: 

June 30, 2020

Author(s):

Arya Ebrahimpour and Barbara Earles

Publication:

Symposium Papers

Volume:

341

Abstract:

Accelerated Bridge Construction (ABC) technologies are being adopted by state transportation departments. One particular ABC technology is the use of precast concrete members joined with mechanical connectors. However, there are concerns about these connections in moderate-to-high seismic regions. A study was carried out for the Idaho Transportation Department (ITD) on the seismic performance of precast columns with grouted couplers versus the conventional cast-in-place columns. Experimental data provided the necessary input to model the grouted couplers. Using the OpenSees finite element analysis program, selected bridges were subjected to the seismic conditions of the most seismically active location in Idaho. Under seismic conditions considered, the stresses in both the longitudinal reinforcing bars and the grouted coupler regions are found to be well within acceptable ranges. The study resulted in recommendations on allowable column drifts, a list of approved grouted rebar couplers, and typical detail drawings for inclusion in the ITD’s Bridge Manual.


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.


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