Response of Reinforced Concrete Columns Under Temperature Induced Transient Creep Strain

Response of Reinforced Concrete Columns Under Temperature Induced Transient Creep Strain
Author: Saleh Mohammad Alogla
Publisher:
Total Pages: 256
Release: 2019
Genre: Electronic dissertations
ISBN: 9781392074220

Structural members experience significant creep deformations in later stages of fire exposure and are susceptible to failure due to temperature induced creep strains. Fire in a concrete structure can burn for several hours, and temperatures in concrete and reinforcing steel can exceed 500 °C. At such temperatures, high levels of creep strains can develop in concrete and steel, especially in reinforced concrete columns. However, temperature induced creep strains are not fully accounted for in evaluating fire resistance of concrete members even through advanced analysis, and there is a lack of data on high-temperature creep strains for specific types of concrete. To overcome current limitations, comprehensive experiments on evolution of transient creep strain are undertaken under various heating and loading regimes. Transient creep tests are conducted in the temperature range of 20 °C to 750 °C on four types of concrete; normal strength concrete, steel fiber reinforced concrete, high strength concrete, and high strength concrete with polypropylene fibers. The test variables include temperature, load level, rate of heating, strength of concrete and presence of fibers. Data from these tests indicate that transient creep strain constitutes a significant portion of the total strain developed during high-temperature exposure. Data also affirm that temperature range and stress level have significant influence on transient creep strain. However, rate of heating and presence of fibers have only a moderate influence on the extent of transient creep in concrete. Presence of steel fibers in normal strength concrete slightly reduce transient creep strain, while the presence of polypropylene fibers in high strength concrete leads to higher transient creep strain. Generated data from experiments is then utilized to propose temperature and stress dependent creep strain relations for concrete. These transient creep strain relations can be implemented in fire resistance evaluation of concrete members. To account for transient creep in undertaking fire resistance analysis of reinforced concrete (RC) columns, a three-dimensional finite element based numerical model is developed in ABAQUS. Temperature-induced creep strains in concrete and reinforcing steel are explicitly accounted for in this advanced analysis. The model also accounts for temperature induced degradation in concrete and reinforcing steel, and material and geometrical nonlinearities. The validity of the model is established by comparing fire response predictions generated from the model with measured response parameters in fire tests on RC columns. Results from the analysis clearly indicate that transient creep strain significantly influences the extent of deformations when the temperatures in concrete exceed 500 °C for stress level of 40% or more, and this in turn influences fire resistance of RC columns. The validated model is applied to assess the influence of transient creep on fire response of RC columns under different conditions, including different fire scenarios, load level, and number of exposed sides in a column. Results from the numerical studies clearly indicate that severe fire exposure induces higher creep strains in RC columns in much shorter duration than exposure to a standard building fire. Moreover, asymmetric thermal gradients resulting from two or three side fire exposure on a column, can increase transient creep effects and, thus, affect fire resistance. The extent of the developed transient creep in concrete columns under various scenarios of fire exposure is highly dependent on the type of concrete. Overall, results from the analysis infer that neglecting transient creep can lead to a lower prediction of deformations and, thus, overestimation of fire resistance in RC columns, particularly when subjected to severe fire exposure scenarios, with higher thermal gradients.

Structural Fire Engineering

Structural Fire Engineering
Author: Venkatesh Kodur
Publisher: McGraw Hill Professional
Total Pages: 481
Release: 2020-02-28
Genre: Technology & Engineering
ISBN: 1260128598

Actionable strategies for the design and construction of fire-resistant structures This hands-on guide clearly explains the complex building codes and standards that relate to fire design and presents hands-on techniques engineers can apply to prevent or mitigate the effects of fire in structures. Dedicated chapters discuss specific procedures for steel, concrete, and timber buildings. You will get step-by-step guidance on how to evaluate fire resistance using both testing and calculation methods. Structural Fire Engineering begins with an introduction to the behavioral aspects of fire and explains how structural materials react when exposed to elevated temperatures. From there, the book discusses the fire design aspects of key codes and standards, such as the International Building Code, the International Fire Code, and the NFPA Fire Code. Advanced topics are covered in complete detail, including residual capacity evaluation of fire damaged structures and fire design for bridges and tunnels. Explains the fire design requirements of the IBC, IFC, the NFPA Fire Code, and National Building Code of Canada Presents design strategies for steel, concrete, and timber structures as well as for bridges and tunnels Contains downloadable spreadsheets and problems along with solutions for instructors

Thermal Stresses IV

Thermal Stresses IV
Author: R.B. Hetnarski
Publisher: Elsevier
Total Pages: 557
Release: 1996-05-10
Genre: Technology & Engineering
ISBN: 0080542816

This is the fourth volume of the handbook Thermal Stresses. Following the principles established when the first volume was published in 1986, the fourth volume consists of six separate chapters prepared by specialists in the field. Each chapter is devoted to a different topic in the area of Thermal Stresses. Many results have been published for the first time in Thermal Stresses IV. The exposition of the material is on the state-of-the art level, which should be appropriate for graduate students, researchers, and engineers specializing in the field of stress analysis. In most cases the material is presented with some historical perspective.A large number of references provided will allow the readers to augment their knowledge, after studying a particular chapter.

Elevated Temperature Response of Reinforced Concrete Slabs

Elevated Temperature Response of Reinforced Concrete Slabs
Author: Attiyah Ali
Publisher: LAP Lambert Academic Publishing
Total Pages: 224
Release: 2014-01
Genre:
ISBN: 9783659516191

The fire resistance of reinforced concrete structures is one of the important issues considered in their design. One of the major problems in analyzing concrete structures using finite element method is the constitutive law used to model their stress-strain behavior. This book presented a numerical method developed to analyze the thermal and structural response of reinforced concrete slabs in elevated temperatures. A finite element approach was used for both thermal and structural analyses, where the effect of high temperature on the mechanical and thermal properties of concrete and steel are taken into account. A model for the stress-strain relationship of concrete at normal temperature was proposed, where it considered four stages of behavior: elastic, elastic-damage, elasto-plastic, and elastic-softening-damage. Based on the principles of continuum damage mechanics, a constitutive law was developed by adding a parameter resembling the area and number of cracks propagating during loading. This model could represent the softening behavior of concrete for different specimen sizes.

International Handbook of Structural Fire Engineering

International Handbook of Structural Fire Engineering
Author: Kevin LaMalva
Publisher: Springer Nature
Total Pages: 530
Release: 2021-10-12
Genre: Technology & Engineering
ISBN: 3030771237

This Handbook is focused on structural resilience in the event of fire. It serves as a single point of reference for practicing structural and fire protection engineers on the topic of structural fire safety. It is also stands as a key point of reference for university students engaged with structural fire engineering.

Urban Habitat Constructions Under Catastrophic Events

Urban Habitat Constructions Under Catastrophic Events
Author: Federico M. Mazzolani
Publisher: CRC Press
Total Pages: 477
Release: 2010-08-30
Genre: Technology & Engineering
ISBN: 0203833627

COST is an intergovernmental framework for European Cooperation in Science and Technology, allowing the coordination of nationally-funded research on a European level. Part of COST was COST Action C26Urban Habitat Constructions Under Catastrophic Events which started in 2006 and held its final conference in Naples, Italy, on 16-18 September 201