scholarly journals Experimental investigation on structural concrete masonry in fire: emphasis on the thermal behavior and residual strength

2021 ◽  
Vol 14 (4) ◽  
Author(s):  
Davi Fagundes Leal ◽  
Rafael Henrique Dupim ◽  
Jorge Munaiar Neto ◽  
Márcio Roberto Silva Corrêa
Keyword(s):  
Experimental Investigation ◽  
Thermal Behavior ◽  
High Temperatures ◽  
Room Temperature ◽  
Load Capacity ◽  
Concrete Strength ◽  
Fire Exposure ◽  
Compression Tests ◽  
Standard Fire ◽  
In Fire

abstract: This paper aims to analyze the thermal behavior and residual mechanical properties of concrete hollow-blocks structural masonry and its component materials in fire situation using experimental investigation. Compression tests were carried out on blocks, prisms and small walls at room temperature and after being exposed for 70 minutes to the ISO 834 Standard Fire. The test at high temperatures was run using a furnace powered by natural gas and instrumented with thermocouples to measure temperatures in the specimens. The influence of the initial concrete strength on masonry behavior was evaluated considering the use of blocks with different strengths at room temperature. In addition, exposure to fire was also investigated considering masonry elements with no coverings and submitted to two different fire exposure conditions: one or both sides. The results indicate a substantial loss in the masonry load capacity at high temperatures, especially in cases of fire exposure on both sides, where the residual compressive strength resulted, on average, between 20% and 27% for the blocks and approximately 14% for prisms and small walls. Its performance with fire heating up on only one face is much higher, with an average residual masonry strength equal to 46% compared to its strength at room temperature. The obtained results are also useful for evaluating masonry regarding the integrity and thermal insulation criteria, the latter achieved with little over 60 minutes of testing.

Drywall Thermal Properties Exposed to High Temperatures and Fire Condition

2013 ◽  
Vol 62 (1) ◽  
Author(s):  
Md Azree Othuman Mydin
Keyword(s):  
Thermal Properties ◽  
High Temperatures ◽  
Fire Resistance ◽  
Residential Buildings ◽  
Cost Effective ◽  
Standard Fire ◽  
Performance Requirements ◽  
Cost Effective Technique ◽  
Fire Barrier ◽  
In Fire

Drywall is a widespread fire barrier used in house and general building construction. Drywall partitions and ceiling membranes are possibly the most common fire resistant construction approach employed in an extensive range of building types. The utilization of drywall board as prime fire protection of light-flame wood or steel construction is ubiquitous. Drywall board based systems are among those now broadly used, as walls or ceilings and it is principally employed as lining material in light-weight construction, which is a competent and cost effective technique of providing flexible partitioning assemblies in commercial and residential buildings. The thickness of the drywall board lining and the configuration of the framing can be flexibly changed to meet specified fire performance requirements. The use of such systems is increasing every day and there demands to be more research on their properties and behaviour. This paper will presents the properties of drywall board which will includes the assemblies and standard fire tests and the thermal properties of drywall in general and includes suggested properties of drywall by different researchers. Drywall boards shrink and crack at high temperatures, and this leads to collapse of parts of the drywall boards in fire. Fall-off of gypsum in fire affects the fire resistance of the assembly considerably, and cannot be overlooked when evaluating the fire resistance of drywall assemblies

Influence of High Temperatures on the Mechanical Properties of Wood Bio-Concretes

2022 ◽  
Author(s):  
Amanda Lorena Dantas Aguiar ◽  
M’hamed Yassin Rajiv da Gloria ◽  
Romildo Dias Toledo Filho
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperatures ◽  
Room Temperature ◽  
Plant Biomass ◽  
Compression Tests ◽  
Wood Degradation ◽  
Cementitious Matrix ◽  
Wood Shavings ◽  
Temperature Reference

The use of wood wastes in the production of bio-concrete shows high potential for the development of sustainable civil construction, since this material, in addition to having low density, increases the energy efficiency of buildings in terms of thermal insulation. However, a concern arising from the production of bio-concretes with high amounts of plant biomass is how this material behaves when subjected to high temperatures. Therefore, this work aims to evaluate the influence of high temperatures on the mechanical properties of wood bio-concretes. The mixtures were produced with wood shavings volumetric fractions of 40, 50 and 60% and cementitious matrix composed of a combination of cement, fly ash and metakaolin. Uniaxial compression tests and scanning electron microscopy (SEM) were performed, with bio-concrete at age of 28 days, at room temperature (reference) and after exposure to temperatures of 100, 150, 200 and 250 °C. The density and compressive strength of the bio-concrete gradually decreased with increasing biomass content. Up to 200 °C, reductions in strength and densities less than 19% and 13%, respectively, were observed. At 250 °C, reductions of compressive strength reached 87%. Analysis performed by SEM showed an increase in the number of cracks in the wood-cementitious matrix interface and wood degradation by increasing the temperature.

scholarly journals Flexural Behavior of Fire-Damaged Prefabricated RC Hollow Slabs Strengthened with CFRP versus TRM

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2556
Author(s):  
Zheng-Ang Sui ◽  
Kun Dong ◽  
Jitong Jiang ◽  
Shutong Yang ◽  
Kexu Hu
Keyword(s):  
Failure Modes ◽  
Early Stage ◽  
Load Capacity ◽  
Peak Load ◽  
Flexural Behavior ◽  
Masonry Building ◽  
Fire Exposure ◽  
Standard Fire ◽  
Four Point Bending ◽  
Strengthening Technique

In this paper, carbon fiber reinforced polymer (CFRP) and textile reinforced mortar (TRM) strengthening techniques were proposed to retrofit and strengthen fire-damaged prefabricated concrete hollow slabs. A total of six slabs, from an actual multi-story masonry building, were tested to investigate the flexural performance of reinforced concrete (RC) hollow slabs strengthened with TRM and CFRP. The investigated parameters included the strengthening method (CFRP versus TRM), the number of CFRP layers, and with or without fire exposure. One unstrengthened slab and one TRM strengthened slab served as the control specimens without fire exposure. The remaining four slabs were first exposed to ISO-834 standard fire for 1 h, and then three of them were strengthened with CFRP or TRM. Through the four-point bending tests at ambient temperature, the failure modes, load and deformation response were recorded and discussed. Both CFRP and TRM strengthening methods can significantly increase the cracking load and peak load of the fire-damaged hollow slabs, as well as the stiffness in the early stage. The prefabricated hollow slabs strengthened by CFRP have better performance in the ultimate bearing capacity, but the ductility reduced with the increase of CFRP layers. Meanwhile, the TRM strengthening technique is a suitable method for the performance improvement of fire-damaged hollow slabs, in terms of not only the load capacity, especially the cracking load, but also the flexural stiffness and deformation capacity.

scholarly journals Lightweight cementitious composites containing cenospheres and polypropylene fibres after exposure to high temperatures

2020 ◽  
Vol 322 ◽  
pp. 01028
Author(s):  
Wojciech Szymkuć ◽  
Piotr Tokłowicz
Keyword(s):  
Thermal Conductivity ◽  
Experimental Investigation ◽  
Compressive Strength ◽  
High Temperatures ◽  
Room Temperature ◽  
Cementitious Composites ◽  
Low Density ◽  
Polypropylene Fibres ◽  
Residual Compressive Strength ◽  
Positive Effect

The paper presents the results of experimental investigation of lightweight cementitious composites with cenospheres (LCCC) exposed to high temperatures. We showed the positive effect of cenospheres on post- fire residual compressive strength in previous papers. This paper focuses on the LCCC with the addition of polypropylene (PP) fibres. Specimens are heated up to 400, 600, 800, 1000 and 1200 °C. Then they are cooled to ambient temperature and their residual flexural and compressive strength is tested. The results are compared with non-heated specimens with compressive strength above 50 MPa. For plain LCCC composites, the results show significant improvement of residual compressive strength in comparison with typical concretes. No significant changes of compressive strength are found after exposure to temperatures up to 600°C – more than 85 % of the residual compressive strength is retained after exposure to this temperature for both mixes. Polypropylene fibres are found to be a successful mean to mitigate spalling without significantly lowering neither ambient nor residual compressive strength. Moreover, designed composite has low density and low thermal conductivity at room temperature.

scholarly journals FIRE RESPONSES AND RESISTANCE OF CONCRETE-FILLED STEEL TUBULAR FRAME STRUCTURES

2010 ◽  
Vol 10 (02) ◽  
pp. 253-271 ◽  
Author(s):  
MIN YU ◽  
XIAOXIONG ZHA ◽  
JIANQIAO YE ◽  
YI Li
Keyword(s):  
Finite Element ◽  
Fire Resistance ◽  
Load Capacity ◽  
Element Model ◽  
Dynamic Responses ◽  
Frame Structures ◽  
Steel Beams ◽  
Standard Fire ◽  
Cfst Columns ◽  
In Fire

This paper presents the results of dynamic responses and fire resistance of concrete-filled steel tubular (CFST) frame structures in fire conditions by using the nonlinear finite element method. Both strength and stability criteria are considered in the collapse analysis. The frame structures are constructed with circular CFST columns and steel beams of I-sections. In order to validate the finite element solutions, the numerical results are compared with those from a fire resistance test on CFST columns. The finite element model is then adopted to simulate the behavior of frame structures in fire. The structural responses of the frames, including the critical temperature and fire-resisting limit time, are obtained for the ISO-834 standard fire. Parametric studies are carried out to show their influence on the load capacity of the frame structures in fire. Suggestions and recommendations are presented for possible adoption in future construction and design of similar structures.

scholarly journals Elastomer Spacers in Fire Conditions

2017 ◽  
Vol 26 (3) ◽  
pp. 109-119
Author(s):  
Paweł Roszkowski ◽  
Bartłomiej Sędłak ◽  
Paweł Sulik
Keyword(s):  
Thermal Degradation ◽  
Fire Resistance ◽  
Load Capacity ◽  
Combustible Material ◽  
Cavity Depth ◽  
Standard Fire ◽  
Degradation Rates ◽  
In Fire ◽  
Resistance Performance ◽  
Fire Conditions

Abstract In the paper, fire resistance of linear joints seal made of elastomer spacers under standard fire conditions, and thermal degradation range of EPDM elastomeric spacers are investigated. The geometry of elastomer spacer joints is important not only for their load capacity under normal conditions - thickness, width, and cavity depth can also influence fire resistance performance. Linear joints of different thicknesses and widths have been tested. The fire insulation and fire integrity were verified for various arrangements. Relatively low thermal degradation rates have been measured, given that EPDM is a combustible material.

scholarly journals Thermal Behavior of Tunnel Segment Joints Exposed to Fire and Strengthening of Fire-damaged Joints with Concrete-filled Steel Tubes

2019 ◽  
Vol 9 (9) ◽  
pp. 1781 ◽  
Author(s):  
Bo Wu ◽  
Yuechun Luo ◽  
Jianbo Zang
Keyword(s):  
Thermal Behavior ◽  
Joint Strength ◽  
Room Temperature ◽  
Full Scale ◽  
Shield Tunnel ◽  
Flexural Stiffness ◽  
Steel Tubes ◽  
Standard Fire ◽  
Joint Gap ◽  
Concrete Filled Steel Tubes

Owing to its discontinuous configuration, segment joint is of particular concern when the shield tunnel lining is exposed to fire. The thermal behavior of such joints when exposed to fire was investigated experimentally in full scale. In addition, the effectiveness of using concrete-filled steel tubes (CFSTs) to restore joint strength after a fire was also investigated. Five full-scale reinforced concrete segment joints were fabricated. Four were exposed to the ISO 834 standard fire for 60 or 120 min, with the fifth serving as a control. Two fire-damaged specimens were then strengthened with CFSTs. All five specimens were then loaded to failure at room temperature. It was found that: (1) The effect of the joint gap on the temperature distribution was observed to change markedly during heating; (2) the temperature of the bolt end was much higher than that of the bolt mid-point, insulating the bolt ends is probably called for; (3) the bearing capacity and flexural stiffness of the fire-damaged segment joints can be significantly improved by strengthening with CFSTs.

Hall mobility in strontium titanate at high temperatures

1976 ◽  
Vol 54 (14) ◽  
pp. 1482-1487 ◽  
Author(s):  
G. Perluzzo ◽  
J. Destry
Keyword(s):  
Experimental Investigation ◽  
Charge Density ◽  
Strontium Titanate ◽  
High Temperatures ◽  
Hall Mobility ◽  
Room Temperature ◽  
Transport Theory ◽  
Phonon Modes ◽  
Charge Densities ◽  
Large Polaron

We report on an experimental investigation of Hall mobility in the polar semiconductor SrTiO3, in the temperature range where thermal energies are comparable to the energies of the interacting phonon modes. We find, for all crystals measured, i.e. for charge densities from 9.6 × 1020 cm−3 to 4.1 × 1017 cm−3, a mobility decreasing with an increase in temperature for 300 K < T < 650 K, from ~5 cm2 V−1 s−1 at room temperature to ~1.5 cm2 V−1 s−1 at 650 K. A slight dependence of mobility on charge density is observed, in that the crystals with higher charge density have the higher mobility. Finally, we interpret our results in terms of existing large polaron transport theory.

scholarly journals Room-temperature deformation of single crystals of ZrB2 and TiB2 with the hexagonal AlB2 structure investigated by micropillar compression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhenghao Chen ◽  
Bhaskar Paul ◽  
Sanjib Majumdar ◽  
Norihiko L. Okamoto ◽  
Kyosuke Kishida ◽  
...  
Keyword(s):  
Single Crystals ◽  
Plastic Flow ◽  
Room Temperature ◽  
Resolve Shear Stress ◽  
Temperature Deformation ◽  
Slip Systems ◽  
Compression Tests ◽  
Plastic Deformation Behavior ◽  
Bulk Single Crystals ◽  
Micropillar Compression

AbstractThe plastic deformation behavior of single crystals of two transition-metal diborides, ZrB2 and TiB2 with the AlB2 structure has been investigated at room temperature as a function of crystal orientation and specimen size by micropillar compression tests. Although plastic flow is not observed at all for their bulk single crystals at room temperature, plastic flow is successfully observed at room temperature by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> in ZrB2 and by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> in TiB2. Critical resolve shear stress values at room temperature are very high, exceeding 1 GPa for all observed slip systems; 3.01 GPa for {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> slip in ZrB2 and 1.72 GPa and 5.17 GPa, respectively for {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> slip in TiB2. The identified operative slip systems and their CRSS values are discussed in comparison with those identified in the corresponding bulk single crystals at high temperatures and those inferred from micro-hardness anisotropy in the early studies.

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