تصرف البلاطات الخرسانية ذاتية الرص المعرضة الى درجات الحرارة العالية تحت تاثير الاحمال الساكنة والصدمية

The Performance of Self Compacting Concrete Slab Exposed to High Temperature Under Static and Dynamic

The aim of this study to Evaluate the effect of high temperatures on specimens of Self-compacted concrete in slabs under static and impact loads . The study contents the experimental work to investigate the effect of high temperatures on some properties of self-Compacted concrete. Fifty four concrete slab samples has been casted with dimensions of ( 500*500*50mm), the specimens were exposed to high temperature by using furnace manufactured for this purpose for (2hrs) then cooled by two methods, gradually by lefting them in the air, and suddenly by using water , After that the specimens were tested to study the effect of different temperature levels(100,300,500,700)° C and cooling rate (gradually and sudden cooling conditions) on the behavior of reinforced concrete slabs under static and dynamic loads, and comparing the results with specimens without burning (reference specimens). The results showed decreasing in bending strength and Toughness of the slabs reinforced after exposure to high temperatures compared with the reference slabs . High temperatures decreased the value of the maximum load for slabs in percentage (0.398%,7.56%,15.27%,29%) compared with the reference slab after exposure to temperature change (100,300,500,700)° C and cooled gradually in air after heating, while the decreasing reached ( 2.12%,10.76%,24.3%,39.97% ) compared with the reference slab at the same temperatures when cooled suddenly by water. This study also has been investigated the behavior of reinforced concrete slabs Exposed to high temperatures under the influence of dynamic impact load and comparing these results with concrete reference slab , Where the tests using the steel structure used in dynamic loads which provided with Linear Variable displacement transducers under the slab. These data was recorded for a period of time begins at the moment Damping in slab occur , Curves were drawn to show (displacement – time relation of slab), The results showed decreasing of slabs impact resistance (the number of blows needed to penetrate ) with the increasing of temperatures. As well as the temperature increased the max displacement and time extinguishing of concrete slabs. where in used the results showed that the reinforced slabs cooled gradually by the air after heating has a dynamic properties better than those which cooled suddenly by water.