Vapor Pressure Modeling for Fire Damage Assessment of HPC

2009 ◽  
Vol 417-418 ◽  
pp. 509-512
Author(s):  
Jie Zhao ◽  
Zhan Qi Guo ◽  
Gai Fei Peng
Keyword(s):  
Vapor Pressure ◽  
Damage Assessment ◽  
High Performance ◽  
High Performance Concrete ◽  
Fem Analysis ◽  
Expansion Method ◽  
Ideal Gas ◽  
Fire Damage ◽  
Severe Damage ◽  
Vapor Pressure Determination

High-performance concrete will undergo severe damage under fire conditions. It is well known that vapor pressure induced by high temperatures plays an important role in the damaging process. This paper presents a method of vapor pressure modeling, called equivalent expansion method, which can be implemented in FEM analysis. The modeling procedure consists of two parts, i.e. vapor pressure determination and vapor pressure modeling incorporated in FEM analysis. In order to make analysis more accurate, steam table is employed instead of ideal gas equation.

Modeling of Vapor Pressure Build-Up in Heated High-Performance Concrete

2012 ◽  
Vol 204-208 ◽  
pp. 3691-3694
Author(s):  
Jie Zhao ◽  
Jian Jun Zheng ◽  
Gai Fei Peng
Keyword(s):  
High Temperature ◽  
Vapor Pressure ◽  
Prediction Model ◽  
High Performance ◽  
High Performance Concrete ◽  
Dominant Role ◽  
Concrete Structures ◽  
Mechanism Study ◽  
Material Degradation ◽  
Temperature Conditions

Under high temperature conditions, such as fire, high-performance concrete will undergo material degradation or even spalling. Spalling is the most detrimental to concrete structures. To prevent concrete from spalling, the mechanism should be understood. Since the build-up vapor pressure in concrete is supposed to play a dominant role in spalling, a vapor pressure prediction model is proposed in this paper to quantitatively analyze the vapor pressure, which can be used for the spalling mechanism study.

scholarly journals Damage Assessment using Acoustic Emission on Concrete Beam

2020 ◽  
Vol 9 (3) ◽  
pp. 2977-2981
Keyword(s):  
Acoustic Emission ◽  
Damage Assessment ◽  
High Performance ◽  
High Performance Concrete ◽  
Bending Test ◽  
Ultra High Performance Concrete ◽  
Reliable Technique ◽  
Damage Level ◽  
Three Point Bending ◽  
Selection Of

The selection of reliable technique for damage assessment is important in civil engineering structure. The present study proposed Acoustic emission (AE) technique by using the fundamental AE parameter to evaluate damage accumulated on Ultra High-Performance Concrete (UHPC) specimens. The UHPC beam with dimension of 515 mm x 98 mm x 98 mm was tested under three-point bending test with stepwise flexural load. In order to detect and to collect the AE data, Micro-SAMOS (μ-SAMOS) digital AE system and R6I sensors type were used while data analyses were carried out using AEwin software. The damage level that take place during increasing static loading on tested concrete beams and the mechanism was successfully evaluated using the AE technique.

Fire-Damage or Freeze-Thaw of Strengthening Concrete Using Ultra High Performance Concrete

2009 ◽  
Vol 79-82 ◽  
pp. 2047-2050 ◽  
Author(s):  
Min Gin Lee ◽  
Yi Shuo Huang
Keyword(s):  
High Temperature ◽  
High Performance ◽  
High Performance Concrete ◽  
Fire Damage ◽  
Ultra High Performance Concrete ◽  
Freeze Thaw ◽  
Concrete Members ◽  
Repair Materials ◽  
Environmental Durability ◽  
Temperature Exposure

There are some reinforced concrete structures exposed to severe environmental conditions might require maintenance or strengthening. Many of these severe circumstances are the result of extreme climate conditions such as low temperature, freeze–thaw action, fire attack, and exposure to deicing salts. Because of this, the environmental durability of both the repair materials and methods used in rehabilitation applications are of utmost importance. A small fire can reach 250°C, while a common blaze can easily produce temperatures of around 800°C. In major conflagrations the temperature can even reach 1100°C. At this level, the heat affects most materials, provoking the spontaneous combustion of some of them and affecting the resistance of others. However, very little research has been performed in evaluating the environmental durability of strengthening materials for concrete members. Very little work has been done on the effects of freeze–thaw cycling on bonding and repair materials. In this study, ultra high performance concrete (UHPC) was used to investigate the effect of strengthening concrete members by fire-damage test or freeze-thaw test. The results show that the mechanical properties of UHPC possess high strength, toughness, and freeze-thaw resistance. The CFRP (carbon fiber reinforced plates) wrapping specimens exposed at 300 °C showed totally failure with the deterioration of the adhesive. The UHPC with bonding 10 mm thickness specimens exposed at 400 °C and duration of 1 hour still in good shape. The UHPC with 1-cm or 2-cm thickness on strengthening concrete members could be obtained specific retrofit effects. The performance of UHPC specimens is better than those of CFRP wrapping specimens during high temperature exposure. The results of slant shear tests show that the bond strength of PC/PC, UHPC/PC and UHPC/UHPC decreased significantly after 600 freeze–thaw cycles or high temperature exposure.

Fire Spalling Modeling of High Performance Concrete

2011 ◽  
Vol 52-54 ◽  
pp. 378-383 ◽  
Author(s):  
Jie Zhao ◽  
Jian Jun Zheng ◽  
Gai Fei Peng
Keyword(s):  
Thermal Stress ◽  
High Temperature ◽  
Vapor Pressure ◽  
High Performance ◽  
High Performance Concrete ◽  
Damage Model ◽  
Concrete Structures ◽  
Anisotropic Damage ◽  
Material Degradation ◽  
Moisture Contents

Under high temperature conditions, such as fire, high performance concrete will undergo material degradation or even spalling. Spalling is the most detrimental damage to concrete structures. To prevent concrete from spalling, the mechanism should be understood. In this paper, an anisotropic damage model, in which both the thermal stress and vapor pressure are incorporated, is presented to analyze the spalling mechanism. The spalling phenomenon is studied based on two cases of different moisture contents. It is concluded that when the vapor pressure is present, concrete will behave much more brittlely.

Modeling of Moisture Distribution Evolution in High-Performance Concrete under Fire Exposure

2014 ◽  
Vol 629-630 ◽  
pp. 279-283
Author(s):  
Jie Zhao ◽  
Gai Fei Peng
Keyword(s):  
Vapor Pressure ◽  
High Performance ◽  
High Performance Concrete ◽  
Water Saturation ◽  
Initial Moisture Content ◽  
Moisture Distribution ◽  
Distribution Analysis ◽  
Vapor Pressure Gradient ◽  
Fire Conditions

High-performance concrete (HPC) will undergo severe damage under fire conditions. It is well known that vapor pressure induced by high temperatures plays an important role in the damaging process. Therefore, the determination of the moisture distribution evolution in concrete is essential to the damage analysis of heated HPC. This paper presents a numerical method for the prediction of the moisture distribution evolution in HPC under fire conditions. In the method, the vapor pressure and the moisture transport induced by the vapor pressure gradient are analyzed. The effect of the thermal decomposition on the moisture distribution and the effects of the slippage flow and the water saturation degree on the permeability are considered. The proposed method is applied to the moisture distribution analysis of a concrete cube with 90% initial moisture content under fire conditions and can be further used for the analysis of the thermal damage of heated HPC.

Mesoscopic Thermal-Mechanical Fire Damage Modeling of High Performance Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1095-1098
Author(s):  
Jie Zhao ◽  
Jian Jun Zheng ◽  
Gai Fei Peng ◽  
Klaas van Breugel
Keyword(s):  
Moisture Transport ◽  
Damage Evolution ◽  
High Performance ◽  
High Performance Concrete ◽  
Damage Model ◽  
Damage Mechanism ◽  
Mechanical Degradation ◽  
Anisotropic Damage ◽  
Fire Damage ◽  
Material Degradation

High performance concrete will undergo thermal-mechanical degradation or even spalling under high temperature conditions, such as fire, and the safety of concrete structures will be endangered. To prevent concrete from fire damage, the damage mechanism should be thoroughly understood. In this paper, an anisotropic damage model is presented to analyze the thermal-mechanical degradation of concrete. The vapor pressure and the moisture transport are taken into account. The damage evolution history can be traced with the temperature propagation and the degree of material degradation can be predicted through the model.

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