Urban Habitat Constructions Under Catastrophic Events

Urban Habitat Constructions Under Catastrophic Events
Author: Federico M. Mazzolani
Publisher: CRC Press
Total Pages: 1068
Release: 2010-08-27
Genre: Technology & Engineering
ISBN: 0203833635

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

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.

Seismic Design and Performance

Seismic Design and Performance
Author: T.G. Sitharam
Publisher: Springer Nature
Total Pages: 406
Release: 2021-03-26
Genre: Science
ISBN: 9813340053

This volume presents select papers presented at the 7th International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. The papers discuss advances in the fields of soil dynamics and geotechnical earthquake engineering. Some of the themes include seismic design of deep & shallow foundations, soil structure interaction under dynamic loading, marine structures, etc. A strong emphasis is placed on connecting academic research and field practice, with many examples, case studies, best practices, and discussions on performance based design. This volume will be of interest to researchers and practicing engineers alike.