Effect of longâ€term loading and fire temperatures on mechanical properties of concrete

During a fire, reinforced concrete structures are exposed to high temperatures and subjected to longâ€term action of variable and permanent loads. This paper deals with analysis of influence of fire temperatures and longâ€term action of loads on compression strength and deformability of normal weight concrete. Results of experimental investigations of compression strength and deformability of normalâ€weight concrete subjected to longâ€term load and exposed to high temperature are presented. Specimens in the shape of prisms of normalâ€weight concrete were subjected to longâ€term compression of intensity η(t) = σc/fc (Ï„) = 0,3. The longâ€term compression was sustained for 400 days. Some of the specimens were heated (at 250 °C and 450 °C) before application of longâ€term load; other specimens were heated after application of longâ€term load. The paper presents coefficient of service conditions for concrete subjected to longâ€term load and exposed to high temperature that gives opportunity to evaluate compression strength and deformation properties of concrete. IlgalaikÄ—s apkrovos ir gaisro temperatÅ«rų įtaka betono mechaninÄ—ms savybÄ—ms Santrauka NagrinÄ—jamas gaisro temperatÅ«rų ir ilgalaikÄ—s apkrovos poveikis sunkiojo betono gniuždomajam stipriui ir deformacinÄ—ms savybÄ—ms. Pateikiami ilgalaike apkrova ir aukÅ¡ta temperatÅ«ra paveikto sunkiojo betono stiprumo ir deformacijų tyrimo rezultatai. Sunkiojo betono bandiniai – prizmÄ—s, apkrautos ilgalaike gniuždanÄia apkrova, kurios intensyvumas η = σc/fc = 0,3. Ilgalaikių bandymų trukmÄ— – 400 parų. Dalis bandinių kaitinti (temperatÅ«ra 250 °C ir 450 °C), prieÅ¡ juos apkraunant ilgalaike apkrova, kiti bandiniai kaitinti po to, kai buvo apkrauti Å¡ia apkrova. Pateikiami ilgalaike apkrova ir aukÅ¡ta temperatÅ«ra paveikto betono patikimumo koeficientai, leidžiantys įvertinti betono gniuždomÄ…jį stiprį ir deformacines savybes. ReikÅ¡miniai žodžiai: betonas, ilgalaikÄ— apkrova, gaisro temperatÅ«ros, gniuždomasis stipris, deformacijos. First Published Online: 14 Oct 201