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International Concrete Abstracts Portal

Showing 1-5 of 11 Abstracts search results

Document: 

SP279

Date: 

March 1, 2011

Author(s):

Editor: Venkatesh Kodur / Sponsored by: Joint ACI- TMS Committee 216

Publication:

Symposium Papers

Volume:

279

Abstract:

This CD-ROM contains 10 papers that were presented at sessions sponsored by Joint ACI-TMS Committee 216 at the ACI Fall 2008 Convention held in St. Louis, MO, and the ACI 2010 Spring Convention in Chicago, IL. The papers present some of the latest research findings on the fire performance of concrete. They provide research results from both experimental and numerical studies on various aspects, ranging from high temperature material properties to advanced computer models for tracing the fire response of reinforced concrete structural members. 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-279

DOI:

10.14359/51682358


Document: 

SP279-07

Date: 

March 1, 2011

Author(s):

Faris Ali and A. Nadjai

Publication:

Symposium Papers

Volume:

279

Abstract:

Recent studies indicate that high strength concrete is more susceptible to explosive spalling under high temperatures. However, more research is required to support this conclusion preferably on large scale structural elements to produce more realistic results. The first part of this paper presents the outcomes of an experimental investigation to study the fire resistance and performance of full-scale simply supported high strength concrete slabs subjected to the ISO834 fire curve. Three high strength concrete slabs 13920 psi (96 MPa) and 3 normal concrete slabs 6528 psi(45 MPa) were involved in the study. Each slab was loaded with 60% of the EC2 design load and was heated from the bottom side only. The second part of the paper presents a finite element study on the fire resistance of concrete slabs. A three-dimensional model of the reinforced concrete slabs taking into account exposure to high temperatures, steel reinforcement and cracks propagation was built. The model was validated using the tests’ results and a good correlation was obtained. The validated model was used to conduct parametric analyses to study the effect of loading level, heating rate (ISO834, Hydrocarbon and RWS fire curves) and axial restraint on the fire resistance of concrete slabs including an assessment of the thermal-mechanical stresses in the slabs.

DOI:

10.14359/51682970


Document: 

SP279-02

Date: 

March 1, 2011

Author(s):

Cristian Maluk, Luke Bisby, Giovanni Terrasi, and Mark Green

Publication:

Symposium Papers

Volume:

279

Abstract:

Novel concrete elements are emerging utilizing high performance self-consolidating concrete (HPSCC) reinforced with high-strength, lightweight, and non-corroding carbon fiber reinforced polymer (CFRP) prestressed reinforcement. The fire performance of these elements must be understood before they can be used with confidence. In particular, the bond performance of the novel CFRP reinforcement at elevated temperatures requires investigation. This paper examines the bond performance of a specific type of CFRP tendon as compared with steel prestressing wire. The results of transient elevated temperature bond pullout and tensile strength tests on CFRP tendons and steel prestressing wire are presented and discussed, and show that bond failure at elevated temperature is a complex phenomenon which is influenced by a number of interrelated factors, including the type of prestressing, degradation of the concrete, CFRP, and steel, differential thermal expansion, thermal gradients and stresses, release of moisture from the concrete, and loading. It is shown that CFRP tendons are more sensitive to bond strength reductions than to reductions in tensile strength at elevated temperature.

DOI:

10.14359/51682965


Document: 

SP279-05

Date: 

March 1, 2011

Author(s):

Patrick Bamonte, Roberto Felicetti and Pietro G. Gambarova

Publication:

Symposium Papers

Volume:

279

Abstract:

The assessment of fire safety in a rather slender pretensioned simply-supported beam with a V section is presented in this paper. Such architecturally-valuable thin-walled beams have been used in Italy for the last forty years in the roofs of large industrial or office buildings, where a series of V girders (= secondary beams, with interposed concrete or glass panels) are supported by other girders resting on columns (= primary beams). After several decades since their construction, many of these members exhibit severe symptoms of distress, often in the form of longitudinal cracks, that can significantly reduce the bearing capacity in shear. (These span-wise cracks are mostly due to transverse bending and start propagating close to the supports, along the extrados of the secondary beams, where rain may accumulate because of insufficient or damaged water proofing). The beam in question, with thin and inclined webs, is checked both at the ultimate limit state (ULS) and in fire, with reference to bending, shear (where the traditional truss model is used), and shear-slip close to the supports, where the aforementioned longitudinal cracking may cause a sort of delamination resisted by the partially-corroded stirrups. Reference is mainly made to the provisions of Eurocode 2, but in the check concerning shear transfer along the longitudinal cracks ACI 318-08 comes into play as well. Even if it is rather peculiar for its unusual cross-section, the beam in question offers the opportunity to focus the attention on some general aspects concerning the behavior of prestressed concrete members in fire conditions, and on some weaknesses of past design provisions.

DOI:

10.14359/51682968


Document: 

SP279-10

Date: 

March 1, 2011

Author(s):

Nikhil Raut and Venkatesh Kodur

Publication:

Symposium Papers

Volume:

279

Abstract:

A macroscopic finite element model for tracing the fire response of reinforced concrete (RC)columns is presented. The model accounts for critical factors such as fire induced spalling, various strain components, high temperature material properties, restraint effects, different fire scenarios and failure criteria, in evaluating fire resistance of RC columns. The validity of the model is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. Parametric studies are performed to study the sensitivity of model predictions to different discrtization and meshing parameters and based on the results an optimum mesh size and time increment for fire resistance analysis of RC columns is recommended. Through case studies it is shown that macroscopic finite element models are capable of predicting the fire response of RC columns over a wide range of parameters as encountered in practical situations.

DOI:

10.14359/51682973


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