scholarly journals Simplified calculation of flexural strength deterioration of reinforced concrete T-beams exposed to ISO 834 standard fire

2021 ◽  
Vol 15 (4) ◽  
pp. 123-135
Author(s):  
Nguyen Truong Thang ◽  
Nguyen Hai Viet
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Cross Sections ◽  
Temperature Dependent ◽  
Strength Deterioration ◽  
Standard Fire ◽  
Parametric Studies ◽  
Simplified Calculation ◽  
T Beam

Reinforced concrete (RC) T-shaped cross-section beam (so-called T-beam) is a common structural member in buildings where beams and slabs are monolithically cast together. In this paper, a simplified calculation method based on Russian design standard SP 468.1325800.2019 is introduced to determine the flexural strength of RC T-beams when exposed to ISO 834 standard fire. The idea of 500oC isotherm method, which is stipulated in both Eurocodes (EC2-1.2) and SP 468, is applied associated with specifications of temperature distribution on T-beams’ cross sections and the temperature-dependent mechanical properties of concrete and reinforcing steel. A case study is conducted to explicitly calculate the flexural strength deterioration (FSD) of T-beams compared to that at ambient temperature. A calculation sheet is established for parametric studies, from which the results show that the FSD factor of RC T-beams is adversely proportional to the dimensions of the beam’s web and flange. However, the effect of these components of T-beams is not significant.

scholarly journals REACTION OF R/C SLABS CROSS-SECTIONS TO FIRE, Calculation of simplified substitute temperature loads induced by an unsteady heat flow

2016 ◽  
Author(s):  
Robert Kowalski ◽  
Marian Abramowicz ◽  
Paweł Chudzik
Keyword(s):  
Reinforced Concrete ◽  
Temperature Distribution ◽  
Heat Flow ◽  
Cross Sections ◽  
Average Temperature ◽  
Standard Fire ◽  
Reinforced Concrete Slabs ◽  
Nonlinear Temperature ◽  
Advanced Analysis ◽  
Temperature Loads

<p>An important issue in advanced analysis of reinforced concrete structures exposed to fire is to determine the response of structural elements (cross-sections) to the effect of high temperature. The unsteady heat flow results in a nonlinear temperature distribution. In practical structural calculations performed by simplified computer programs the average temperature value and the appropriate temperature gradient are used. This paper presents substitute values of these parameters and detailed analysis of nonlinear temperature distribution in 20, 25, 30 cm thick reinforced concrete slabs exposed to one-sided standard fire.</p>

scholarly journals Strengthening of a Reinforced Concrete Bridge with Polyurethane-cement Composite (PUC)

2016 ◽  
Vol 10 (1) ◽  
pp. 768-781 ◽  
Author(s):  
Zhang Kexin ◽  
Sun Quansheng
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Bending Strength ◽  
Cement Composite ◽  
Concrete Surface ◽  
Raw Material ◽  
Structure Theory ◽  
Before And After ◽  
Strength And Stiffness ◽  
T Beam

This paper describes a new material, polyurethane-cement composite (PUC), used to strengthen a 29-year-old reinforced T-beam bridge in Harbin, China. Polyurethane-cement composite (PUC) is mixed with polyurethane raw material and cement. This technique is completed by pouring Polyurethane-cement composite (PUC) into the template. Ultimate bearing capacity of the bridge after reinforcement was discussed based on the concrete structure theory. The flexural strength of reinforced concrete T-beam bridges strengthened with Polyurethane-cement composite (PUC) was controlled by the design flexural strength of Polyurethane-cement composite (PUC). The main construction process was introduced which included concrete surface treatment, installing template and pouring. To investigate the feasibility of the strengthening method, load tests were conducted before and after strengthening. The results of concrete strain and deflection show that the capacity of the repaired bridge, including the bending strength and stiffness, is enhanced. The crack width measurement also indicates that this technique could increase the durability of the bridge. Thus, this strengthened technique with polyurethane-cement composite (PUC) is feasible, the bridge load posting possibly is removed through this technique.

Basic Study on Reinforced Concrete Shear Walls Without Boundary Columns Retrofitted by Carbon Fiber Sheets

2014 ◽  
Vol 9 (6) ◽  
pp. 1008-1014 ◽  
Author(s):  
Tomoya Matsui ◽  
◽  
Taiki Saito ◽  
Roy Reyna
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Cross Sections ◽  
Shear Walls ◽  
Shear Wall ◽  
Wire Mesh ◽  
Structural Elements ◽  
Basic Study ◽  
Flexural Mode ◽  
Strength Deterioration

Reinforced concrete (RC) buildings in Peru use low ductility walls, with rectangular cross-sections and reinforced with wire mesh and vertical reinforcement bars at boundary ends, as structural elements. These structural elements have no columns, have small amounts of reinforcing bars and are expected to fail in a brittle manner. In this study, a performance verification test is conducted on the use of carbon fiber sheets (CFS) as a retrofitting method for shear walls without boundary columns. The focus is on retrofitting walls that fail in flexural mode. In other words, although an increase in strength cannot be expected, CFS retrofitting can delay the concrete crushing of the shear wall base that occurs during flexural failure; and the aim is to verify this improvement in deformation performance due to CFS retrofitting. From the test, by retrofitting the RC shear wall without boundary columns with CFS, it was found that postmaximum strength deterioration was more gradual, and deformation performance was improved. And Ultimate limit deformation of specimen which was partially retrofitted at the boundary ends of the wall was larger than that of specimen which was retrofitted over the entire wall span.

scholarly journals THE EFFECT OF HIGH TEMPERATURE ON REINFORCED CONCRETE STRUCTURES

2010 ◽  
Vol 2 (1) ◽  
pp. 12-21 ◽  
Author(s):  
Robertas Zavalis ◽  
Arnoldas Šneideris
Keyword(s):  
Reinforced Concrete ◽  
High Temperature ◽  
Cross Sections ◽  
Concrete Strength ◽  
Temperature Fields ◽  
Concrete Element ◽  
Zone Method ◽  
Standard Fire ◽  
Fire Curve ◽  
Zone Dimension

The article represents the behaviour of reinforced concrete and its components (concrete and reinforcement) under high temperature. The comparing analysis of the experimentally and theoretically obtained results has been performed. The carried out experiment has disclosed that the mechanical properties of concrete alters differently in cases of temperature rise and theoretical reference. The most visible difference has been noticed at a temperature of 100 °C (Fig 4, Fig 5). The main fire resistance calculation basics are discussed. The temperature fields of the reinforced concrete element cross-section are calculated according to the standard fire curve using the program COSMOS/M of the finite element method. Concrete thermal properties, thermal conductivity and specific heat capacity dependence on temperature are taken into account in the model (Fig 10, Fig 11). By means of this model, the corresponding algorithm (Table 2) was made and can be used for obtaining temperature distribution for the reinforced concrete element of different cross-sections. According to the received temperature fields and applying the zone method, the influence of differences in theoretical and experimental results on element load bearing capacity is determined. The residual strength of the element considering the theoretical reduction curve of concrete strength is 5% larger than the results obtained in cases of 30 and 60 minutes heating. 90 and 120 minutes heating indicates that element strength is only 2% larger than the results calculated experimentally. The reduced zone dimension determined due to a decrease in the reduction coefficient at a temperature of 100 °C has affected residual element strength.

Extension of the Zone Method of Eurocode 2 for reinforced concrete columns subjected to standard fire

2016 ◽  
Vol 7 (2) ◽  
pp. 82-96 ◽  
Author(s):  
Marcus Achenbach ◽  
Guido Morgenthal
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Calculation Method ◽  
Concrete Columns ◽  
Temperature Dependent ◽  
Zone Method ◽  
Content Type ◽  
Standard Fire ◽  
Eurocode 2 ◽  
Design Software

Purpose The purpose of this paper is to develop a method suitable for the design of reinforced concrete columns subjected to a standard fire. Design/methodology/approach The Zone Method – a ’simplified calculation method” included in Eurocode 2 – has been developed by Hertz as a manual calculation scheme for the check of fire resistance of concrete sections. The basic idea is to disregard the thermal strains and to calculate the resistance of a cross-section by reducing the concrete cross-section by a “damaged zone”. It is assumed that all fibers can reach their ultimate, temperature dependent strength. Therefore, it is a plastic concept; the information on the state of strain is lost. The calculation of curvatures and deflections is thus only possible by making further assumptions. Extensions of the zone method toward a general calculation method, suitable for the implementation in commercial design software and using the temperature dependent stress–strain curves of the Advanced Calculation Method, have been developed in Germany. The extension by Cyllok and Achenbach is presented in detail. The necessary assumptions of the Zone Method are reviewed, and an improved proposal for the consideration of the reinforcement in this extended Zone Method is presented. Findings The principles and assumptions of the Zone Method proposed by Hertz can be validated. Originality/value An extension of the Zone Method suitable for the implementation in design software is proposed.

Fire Resistance of Bar-Reinforced Concrete Filled Steel Columns

2008 ◽  
Vol 400-402 ◽  
pp. 757-762
Author(s):  
Lei Xu ◽  
Yu Bin Liu
Keyword(s):  
Reinforced Concrete ◽  
Theoretical Model ◽  
Numerical Model ◽  
Cross Sections ◽  
Fire Resistance ◽  
Steel Columns ◽  
Mechanic Model ◽  
Resistance Analysis ◽  
Standard Fire ◽  
Good Agreement

In this paper a numerical model for fire resistance analysis of bar-reinforced concrete filled steel columns with square and circular cross-sections have been put forward. The model has been validated by testing results. There is a good agreement. Used of the theoretical model, the relations between the fire resistance and various parameters have been analyzed. On the basis of that, formulas for the calculation of the fire resistance of bar-reinforced concrete filled square and circular steel columns under ISO-834 Standard Fire Curves are developed respectively. The calculated results have a good agreement with those of mechanic model and test.

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