scholarly journals Temperature influence on creep of reinforced concrete

2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Edmilson Lira Madureira ◽  
Brenda Vieira Costa Fontes
Keyword(s):  
Reinforced Concrete ◽  
Moisture Content ◽  
Alternative Model ◽  
Sustained Load ◽  
Structural Members ◽  
Temperature Influence ◽  
Stress Increase ◽  
Concrete Members ◽  
Over Time ◽  
Creep Strains

abstract: The creep of concrete promotes strains over time in structural members kept under sustained load. It causes the stress decrease on the concrete and the steel stress increase in reinforced concrete members. The moisture content and temperature influence significantly such phenomenon. The creep strains model of the NBR 6118/2014 [1] is, applicable, solely, to those cases of constant stress magnitudes. Reinforced concrete members exhibit variations on the stress magnitudes and, in this way, requires the use of an alternative model for the prediction of the creep strains as the so known the State Model. This report refers itself to temperature influence analysis upon creep strains of reinforced concrete structural members. The results have revealed that temperature speeds up the creep effects and, in this way, the steel yielding caused by the stress increase on the reinforcement bars occurs at earlier ages.

scholarly journals Numerical simulation of the experimental behavior of RC beams at elevated temperatures

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Camille A. Issa ◽  
Ramezan A. Izadifard
Keyword(s):  
Reinforced Concrete ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Material Behavior ◽  
Reinforced Concrete Beams ◽  
Structural Members ◽  
Fire Event ◽  
Concrete Material ◽  
Concrete Members ◽  
Actual Fire

AbstractThe danger of fire is present always and everywhere. The imminent danger depends upon the actual type and length of fire exposure. Reinforced concrete structural members are loadbearing components in buildup structures and are therefore at high risk, since the entire structure might potentially collapse upon their failure. Thus, it is imperative to comprehend the behavior of reinforced concrete members at high temperatures in case of fire. In this study, the mechanical properties of concrete exposed to high temperatures were experimentally determined through the testing of 27 concrete cylinder starting at room temperature and increasing up to 260 °C. The concrete material behavior was implemented into the ABAQUS software and a finite simulation of reinforced concrete beams exposed to actual fire conditions were conducted. The finite element models compared favorably with the available experimental results. Thus, providing a valuable tool that allows for the prediction of failure in case of a fire event.

scholarly journals Seismic Behavior of Reinforced Concrete Members Built with Recycled Aggregate

2019 ◽  
Vol 2 (2) ◽  
pp. 295-306
Author(s):  
Alper Ilki ◽  
Ilyas Saribas ◽  
Caglar Goksu
Keyword(s):  
Reinforced Concrete ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Small Scale ◽  
Concrete Aggregate ◽  
Structural Members ◽  
Recycled Concrete Aggregate ◽  
Rapid Urbanization ◽  
Concrete Members ◽  
Waste Concrete

In connection with rapid urbanization and earthquakes, a huge number of structures have been demolished and generated lots of waste concrete for the last 40 years. Studies on the reclamation of the waste concrete is a pioneer subject for construction sectors in the world. Since the recycling of the waste concrete and reusing of recycled concrete aggregate in the production of new concrete is an important issue for saving of natural resources, economic, sustainable development, significant number of studies have been carried out on this subject. In the scope of this study, a literature review is conducted on the effect of recycled concrete aggregate on mechanical and durability characteristics of small-scale members. Furthermore, structural and seismic performances of full-scale reinforced concrete structural members produced with recycled concrete aggregate are discussed. The test results indicated that the structural members containing recycled aggregate exhibited similar structural performance with their counterparts containing natural aggregates. It was also observed that recycled concrete aggregate did not seem to have an adverse effect on seismic characteristics of the structural members such as ductility.

Predicting reinforced concrete response to blast loads

2013 ◽  
Vol 40 (5) ◽  
pp. 427-444 ◽  
Author(s):  
Eric Jacques ◽  
Alan Lloyd ◽  
Murat Saatcioglu
Keyword(s):  
Reinforced Concrete ◽  
Shock Tube ◽  
Free Field ◽  
Computer Software ◽  
Deformation Characteristics ◽  
Structural Members ◽  
Pressure Impulse ◽  
Concrete Members ◽  
Inelastic Analysis ◽  
Wide Range

Computer software was developed for inelastic analysis of structural members subjected to blast-induced shock waves. The software can predict the dynamic response of structural elements, provided the load–deformation characteristics are defined. The software has built-in capabilities to generate the load–deformation characteristics of common structural and non-structural members. Currently this capability includes reinforced concrete columns, one-way walls, beams, and one-way slabs. The input consists of member geometry, boundary conditions, dynamic material properties, explosive threat parameters, and desired performance levels. The results are presented in graphical format in terms of structural load–deformation characteristics, single degree of freedom displacement – time histories and iso-displacement pressure–impulse diagrams. The program was verified extensively using experimental data generated from simulated explosive loading of reinforced concrete members at the University of Ottawa shock tube testing facility. The shock tube has been shown to generate a wide range of pressure–impulse combinations, accurately simulating free-field detonation of high explosives of various mass and standoff distances.

SHEAR REPAIRED RC BEAM BY FRP BONDING WITH EXTERNAL POST-TENSIONING

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Rumana Choudhury ◽  
T.G. Suntharavaivel ◽  
Nirmal Mandal
Keyword(s):  
Reinforced Concrete ◽  
Shear Capacity ◽  
Rc Beams ◽  
Structural Members ◽  
Shear Cracks ◽  
Shear Strengthening ◽  
Flexural Strengthening ◽  
Concrete Members ◽  
Post Tensioning ◽  
Strengthening Technique

Various factors, including increase in traffic volume and weight, structural aging, and environmental impact, cause damage in structural members. This raises the importance of the maintenance, rehabilitation, and strengthening of reinforced concrete members. External post-tensioning is one of the widely-used strengthening techniques in many countries due to its advantages over other strengthening methods. Although flexural strengthening of existing structural members is a well-established method, shear strengthening of structural members, especially with existing shear cracks, has attained very little attention from researchers. Similarly, external fiber-reinforced polymer (FRP) bonding for shear strengthening of structural members, especially with existing shear cracks, is a relatively new area of research. This paper presents the results of an experimental study on the shear strengthening of reinforced concrete (RC) beams with existing shear cracks by external post-tensioning and external FRP bonding. The test result showed that the combined strengthening technique of external post-tensioning and external FRP bonding can effectively increase the shear capacity of RC beams with existing shear cracks.

scholarly journals Creep strains on reinforced concrete columns

2013 ◽  
Vol 6 (4) ◽  
pp. 537-560 ◽  
Author(s):  
E. L. Madureira ◽  
T. M. Siqueira ◽  
E. C. Rodrigues
Keyword(s):  
Reinforced Concrete ◽  
Concrete Columns ◽  
Sustained Load ◽  
Physical Parameters ◽  
Concrete Element ◽  
Memory State ◽  
Reinforced Concrete Columns ◽  
Steel Bars ◽  
State Models ◽  
Creep Strains

A concrete element when kept under sustained load presents progressive strain over time, associated to the creep. In reinforced concrete columns, such deformations cause the stress increase in the steel bars of the reinforcement and may induce the material to undergo the yielding phenomenon. The pioneering formulations about the creep effect, developed on the base of creep coefficient, are applicable, especially, when the stress magnitude remains constant. Its application to reinforced concrete members, which exhibits change in stress magnitude, requires simplifications of which result the memory models, which have the disadvantage of requiring the storage of the stress history. To overcome the difficulties related to the excessive demand for computer memory, State models have been developed that dispense such robustness of storage. The subject of this work is the analysis of creep deformations in reinforced concrete columns on the base of a state model fixing its physical parameters from results obtained through the NBR 6118/07 formulation. The results showed that, in the elapse of the phenomenon, occurs stresses transfer from the concrete mass to the reinforcement steel bars which, in turn, have the effect of restrain the creep strains, confirming, in some cases, an imminent material yielding condition.

scholarly journals Exploitation of Ultrahigh-Performance Fibre-Reinforced Concrete for the Strengthening of Concrete Structural Members

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Mohammed A. Al-Osta
Keyword(s):  
Reinforced Concrete ◽  
Environmental Conditions ◽  
Design Guidelines ◽  
Fibre Reinforced Concrete ◽  
Structural Members ◽  
Structural Concrete ◽  
Concrete Members ◽  
Service Load ◽  
Durability Performance ◽  
Load Conditions

The repair and strengthening of reinforced concrete members are very important due to several factors, including unexpected increases in load levels and/or the damaging impact of aggressive environmental conditions on structural concrete members. Many researchers have turned to using materials for the repair and strengthening of damaged structures or the construction of new concrete structural members. Ultrahigh-performance fibre-reinforced concrete (UHPFRC), characterized by superior structural and durability performance in aggressive environmental conditions, is one of the materials that have been considered for the repair and strengthening of concrete structural members. The repair or strengthening of concrete structures using UHPFRC needs a thorough knowledge of the behaviour of both the strengthening material and the strengthened concrete structure at service load conditions, in addition to an understanding of the design guidelines governing the use of such materials for effective repair and strengthening. In this study, the recent issues and findings regarding the use of UHPFRC as a repair or strengthening material for concrete structural members are reviewed, analysed, and discussed. In addition, recommendations were made concerning areas where future attention and research on the use of UHPFRC as a strengthening material needs to be focused if the material is to be applied in practice.

Experimental Study on the Effect of Moisture Content on Hysteretic Behavior of Reinforced Concrete Columns

2018 ◽  
Vol 12 (1) ◽  
pp. 47-61
Author(s):  
Wenjuan Lv ◽  
Baodong Liu ◽  
Ming Li ◽  
Lin Li ◽  
Pengyuan Zhang
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Moisture Content ◽  
Early Stage ◽  
Damping Ratio ◽  
Concrete Columns ◽  
Hysteretic Behavior ◽  
Cyclic Test ◽  
Experimental Result ◽  
Reinforced Concrete Columns

Background: For reinforced concrete structures under different humid conditions, the mechanical properties of concrete are significantly affected by the moisture content, which may result in a great change of the functional performance and bearing capacity. Objective: This paper presents an experiment to investigate the influence of the moisture content on the dynamic characteristics and hysteretic behavior of reinforced concrete column. Results: The results show that the natural frequency of reinforced concrete columns increases quickly at an early stage of immersion, but there is little change when the columns are close to saturation; the difference between the natural frequencies before and after cyclic test grows as the moisture content rises. The damping ratio slightly decreases first and then increases with the increase of moisture content; the damping ratio after the cyclic test is larger than before the test due to the development of the micro-cracks. Conclusion: The trend of energy dissipation is on the rise with increasing moisture content, although at an early stage, it decreases slightly. According to the experimental result, a formula for the moisture content on the average energy dissipation of reinforced concrete columns is proposed.

Sign in / Sign up

Export Citation Format

Share Document