Home Books Science. Save For Later. Create a List. Summary Concrete as a construction material goes through both physical and chemical changes under extreme elevated temperatures. The book provides unique insight into: Coupling thermal-mechanical constitutive relation of concrete Exceptional analyses of beams and columns of rectangular section with three surfaces and two adjacent surfaces exposing to high temperature Measurement and analysis of redistribution of internal forces of statically indeterminate structure during heating-loading process Finite element analysis and calculation charts for two-dimensional temperature field of structural members Finite element analysis and simplified calculation method for reinforced concrete structure at elevated temperature With this book, engineers and architects can effectively analyze the effect of high temperature on concrete and materials which will lead to better designs of fire resistant and damage evaluation and treatment after fire.
Measurement and analysis of redistribution of internal forces of statically indeterminate structure during the heating-loading process. Finite element analysis and calculation charts for two-dimensional temperature field of structural members. Finite element analysis and simplified calculation method for reinforced concrete structure at elevated temperature. Read on the Scribd mobile app Download the free Scribd mobile app to read anytime, anywhere.
Start your free 30 days. Page 1 of 1. Close Dialog Are you sure? The transient creep consists of transitional thermal creep TTC and drying creep, however, TTC is the main component of transient creep. It was observed that the expansion of concrete was mainly affected by aggregate nature, whereas, its influence on LITS was negligible.
Furthermore, moister content and heating rate variation did not affect LITS. Moreover, the main factors influencing LITS was stress level and temperature. It was further reported that LITS was observed only during initial heating and did not recover during the subsequent cooling phase. However, temperature higher than the last stage produced additional LITS.
According to Khoury et al. Later on, the experimental results of Khoury et al.
He proposed 4th and 5th order polynomial functions considering the volume portion and types of aggregates. It was observed that the main influencing factors on STC are aggregate type, loading level and its duration. Creep behavior of concrete at high temperature is of significant importance for fire resistance design and post-fire structural assessment. The amount of creep produced at high temperature in few hours is comparable to several decades creep under normal conditions Wu et al.
If the creep is neglected in fire safety design, the calculated fire resistance of members is lower than that of actual fire resistance, and the concrete structure may not be safe Alogla and Kodur Up to date, traditional types of concretes were extensively studied at high temperature. However, the creep behavior of RPC is not well known at high temperature and very little information is available.
Furthermore, the effect of fibers, which becomes a compulsory constituent due to spalling resistant, is also not understood. TS was further investigated at variable loading levels.
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The effect of PP and hybrid PP and steel fibers were evaluated on creeping effects. Experimental results were modeled and fitting equations were proposed. Furthermore, comparative studies were carried out with available literature. This study will be very beneficial for the construction industry as well as academia.
The raw materials used for the preparation of RPC in this study mainly include cement, silica fume, slag, quartz sand, water reducer, steel fiber, PP fiber and polycarboxylic superplasticizer. The physical appearance of raw materials is shown in Fig.
The main properties of various constituents are as follows:. Ordinary Portland cement P. The cement quality was as per the Chinese standard specification GB of common Portland cement. Its ultra-fine powder is dark grey color. The average nominal sizes of 0. The SiO 2 content in quartz sand was more than The straight brass coated steel fiber produced by Changhong Company, Anshan, Liaoning Province was used. Polypropylene fiber is a high-strength fiber made of polypropylene as the main raw material.
The mix proportion of the co-author Zheng et al. In order to minimise the end effect, prism shape specimens, whose length to width ratio is , was used. For each type of RPC, a total of 93 prisms of size The results for each test is the arithmetic mean of the two test results. An electronic balance was used for measurements of materials. The mixing was carried out in horizontal pan type mixer which can be adjusted for revolution at different speeds.
This result in uniform plastic consistency mix. The RPC produced was sufficient workable for construction work. A mini-slump cone was filled with fresh RPC mix on a vibratory table, after the cone is removed and RPC is allowed to spread naturally on the table, then the flow table was dropped 25 times. The average diameter of the spread of RPC shows its workability. Plastic moulds were oiled before filling in 3 layers. Each layer was consolidated using a vibratory table until oozing slurry appears on the surface of RPC.
The top surface was smoothened using a trowel. Steam curing accelerates the hydration reactions and strength of RPC was increased.
Experiment and Calculation of Reinforced Concrete at Elevated Temperatures - Brown Technical
Since RPC microstructure is sufficient compact, and melting of PP fibers provide safe passage for releasing vapors pressure during high temperature, still there is fear of fire-induced spalling owing to high amount of moisture content Zheng et al. Therefore, specimens were subjected to special heat treatment method Zheng et al. The moister content of RPC specimens was lowered up to 2.
The average rate of moister loss per day was 0.
In order to protect the specimens from moister absorption, it were preserved in sealed polyethene bags until the day of testing. In the preliminary trial experiments, the specimens survived explosive spalling during coupled thermo-mechanical loading. This was a serious concern for this study. A purpose built furnace with an opening on upper and lower side was used, which allows simultaneous loading during the heating process.
The test-setup frame and furnace arrangements are shown in Fig. Two special A Nickel-based alloy attachments platens were used below and above the specimen in the furnace for simultaneous transmission of load, heating and transferring the deformation of the specimen to the ambient condition. Allow rods were welded to the ends of platens for transmission of deformation outside of the specimens. The exposed part of the alloy platens were wrapped in insulation material, as a safety precaution.
The length of alloy platen also works as insulator and protects the testing frame and equipment from extreme heating. A K-type thermocouple, mounted in the middle of the furnace was used to measure and control the heating rate. The specimens surface and centre temperature were recorded by Center thermometer. Special steel frame was bolted to the UTM to hold the upper loading platen after failure of the specimen free fall of upper loading platen and protects LVDTS and furnace arrangements from damaging.
In order to measure the center temperature of the specimen, a thermocouple was installed in the centre core of the specimens during the fabrication process.
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The surface temperature was measured on the longitudinal midpoint location of the specimen in diametric opposite directions. The surface thermocouples were installed during specimen adjustment process and it was ensured that the thermocouples keep in touch with the specimen during the whole heating process. WRNK type thermocouple of two sizes were used.
The specimen centre and surface temperature were recorded by 0. The specimens were heated till centre temperature reaches the target temperature. It is evident that the gradient of surface temperature and centre temperature is lower than the furnace and programme temperature. Therefore to display the creep behaviour against temperature a mean reference temperature of the specimen is required. RILEM recommendations proposed a relationship for mean temperature of the specimen during transient heating, which will be hereafter called as reference temperature.
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The formula is given below. The specimen deformation has been transferred to the ambient condition by the attached alloy rods. The alloy rods were welded only with those ends of the platens which are connected with the specimen.