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International Concrete Abstracts Portal

Showing 1-5 of 16 Abstracts search results

Document: 

SP281

Date: 

December 29, 2011

Author(s):

Editors: Ganesh Thiagarajan, Eric Williamson and Christopher Conley / Sponsored by: Joint ACI-ASCE Committee 447 and ACI Committee 370

Publication:

Symposium Papers

Volume:

281

Abstract:

This CD-ROM contains 15 papers that were presented at sessions sponsored by ACI Committees 447 and 370 at the ACI Fall 2010 Convention in Pittsburgh, PA. In this publication, engineers report on how they are approaching the challenging task of predicting the response of structures subjected to blast and impact loading. Both experimental and analytical efforts are represented, often in tandem. The analytical approaches taken include single-degree-of-freedom modeling, highly nonlinear transient dynamic finite element simulations, and coupled Lagrangian-Eulerian simulations. Papers in the publication cover the design and evaluation of new and existing structures, as well as techniques for strengthening existing structures. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-281

DOI:

10.14359/51683562


Document: 

SP281-12

Date: 

December 27, 2011

Author(s):

Charles M. Newberry, John M. Hoemann, Bryan T. Bewick and James S. Davidson

Publication:

Symposium Papers

Volume:

281

Abstract:

This paper discusses simulation methodologies used to analyze large deflection static and dynamic behavior of polymeric foam insulated concrete sandwich wall panels. Both conventionally reinforced cast-on-site panels and precast prestressed panels were considered. The experimental program used for model validation involved component-level testing, as well as both static and dynamic testing of full‐scale wall panels. The static experiments involved single span and double span sandwich panels subjected to near‐uniform distributed loading. The dynamic tests involved spans up to 30 ft tall that were subjected to impulse loads generated by an external explosion. Primary modeling challenges included: (1) accurately simulating prestressing initial conditions in an explicit dynamic code framework, (2) simulating the concrete, reinforcement, and foam insulation in the high strain rate environment, and (3) simulating shear transfer between wythes, including frictional slippage and connector rupture. Correlation challenges, conclusions and recommendations regarding efficient and accurate modeling techniques are highlighted. The modeling methodologies developed are now being used to conduct additional behavioral studies and parametric analyses, and assess and improve methodology currently used in the design of foam insulated precast/prestressed sandwich panels for blast loads.

DOI:

10.14359/51683621


Document: 

SP281-10

Date: 

December 27, 2011

Author(s):

Sarah Orton, Matthew Brune, Joseph Kirby and Matthew Wheeler

Publication:

Symposium Papers

Volume:

281

Abstract:

Carbon fiber anchors can serve to improve the performance of externally applied CFRP (Carbon Fiber Reinforced Polymer) strengthened concrete structures because they do not rely on the bond of the CFRP to the concrete to transfer stresses. This paper seeks to identify the residual strength of externally applied CFRP after damage has been delivered by an instrumented drop-weight impact testing device. The paper further investigates effectiveness of carbon fiber anchors (anchors inserted into predrilled holes and fanned out over the CFRP sheet) in impact damaged specimens. The paper reports the results from 14 impact damaged CFRP strengthened 1.42 m (56 in.) long beams with and without anchors. The research found that impacts from the testing device with a drop height greater than 1.83 m (6 ft) significantly reduced the tensile strength of the CFRP. However, with the use of anchors the same strength can be reached in a damaged CFRP specimen as in an undamaged unanchored specimen. The paper also reports on the effectiveness of the anchors when used to strengthen a reinforced concrete slabs subjected to blast loads and a reinforced concrete beam under impact loading and finds that the anchors are able to fully develop the tensile strength of the CFRP under dynamic loading.

DOI:

10.14359/51683618


Document: 

SP281-15

Date: 

December 27, 2011

Author(s):

Ganesh Thiagarajan, Anirudha K. Vasudevan and Stephen Robert

Publication:

Symposium Papers

Volume:

281

Abstract:

The numerical simulation of the response of reinforced concrete components and structures subjected to blast and impact loads are of vital interest to the design of such structures. Both researchers and designers have a wide variety of choices. Designers often focus on the usage of results from single degree of freedom analyses published in a number of design guides, such as the Unified Facilities Criteria. Researchers often tend to use finite element codes which vary from advanced hydrodynamic codes often used by Army researchers to commercially available codes such as ABAQUS® and LS-DYNA® amongst others. The primary objective of this research is to study the behavior of both high strength concrete and normal strength concrete reinforced with high strength low alloy vanadium (HSLA-V) reinforcement that meets or exceeds blast resistance criteria using conventional materials. The research presented in this paper focuses on the numerical simulation and comparison with experimental data from reinforced concrete slabs using HSLA-V steel. Two sets of experiments and the numerical simulations to compare with the experiments performed are described in this paper. The experimental work involved the fabrication and testing of two types of reinforced concrete panels namely High Strength Concrete with HSLA-V Steel Reinforcing bars (HSC-VR) and Normal Strength Concrete with HSLA-V Steel Reinforcing bars (NSC-VR). The panels were subjected to blast loadings using the Blast Loading Simulator (shock tube) at the U.S. Army Engineering Research and Development Center. Data recorded included pressures at various locations, mid-span displacements from accelerometers and laser devices, and observed damage patterns. The numerical modeling effort focused on using LS-DYNA and attempting the simulation using two commercially available material models. Results from the numerical simulation are compared with the experimental values in order to determine the accuracy of the models. The concrete material models considered were Winfrith Concrete Model and Concrete Damage Model Release 3. Both the models gave deflection values that compared well with the experimental results for normal strength concrete but gave stiffer predictions for high strength concrete.

DOI:

10.14359/51683624


Document: 

SP281-08

Date: 

December 27, 2011

Author(s):

William H. Zehrt, Jr. and Patrick F. Acosta

Publication:

Symposium Papers

Volume:

281

Abstract:

Since its initial publication in 1969, Unified Facilities Criteria (UFC) 3-340-02 (formerly Army Technical Manual 5-1300/Navy Publication NAVFAC-P397/Air Force Manual AFR 88-22) has provided uniquely practical and intuitively straightforward procedures for analyzing and designing blast resistant structures. With its unlimited distribution, UFC 340-02 is the blast design manual of choice of both government explosives safety experts and private A-E firms throughout the world. This paper summarizes updates to the blast design guidance in chapter 4, reinforced concrete design. Detailed data are presented on the revisions in three areas: dynamic increase factor, design of diagonal tension reinforcement in walls and slabs, and prediction of concrete spall and breach. The paper concludes with a brief discussion of future work.

DOI:

10.14359/51683616


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