【摘要】：目前國(guó)內(nèi)外對(duì)普通鋼管混凝土柱的抗火性能開展了較多的研究，而對(duì)輕骨料鋼管混凝土柱火災(zāi)行為的研究還比較少，尤其對(duì)自應(yīng)力及鋼纖維增強(qiáng)輕骨料鋼管混凝土柱的火災(zāi)響應(yīng)及火災(zāi)后力學(xué)性能的研究更加薄弱。本文以頁(yè)巖陶粒做為粗骨料，通過(guò)在混凝土中分別摻入一定量的膨脹劑和鋼纖維制作了兩種不同性質(zhì)的輕骨料鋼管混凝土柱，并以此為對(duì)象開展了一系列輕骨料鋼管混凝土柱的抗火性能研究。由于鋼纖維的加入可有效抑制核心混凝土微裂縫的發(fā)展，改善輕骨料鋼管混凝土的力學(xué)性能；而膨脹劑的加入可在一定程度上提高輕骨料混凝土剛度較低的問(wèn)題。因此，對(duì)自應(yīng)力及鋼纖維增強(qiáng)輕骨料鋼管混凝土力學(xué)性能的研究具有重要的理論意義和工程應(yīng)用價(jià)值。 本文首先以含鋼率和膨脹劑摻量為變化參數(shù)對(duì)9組鋼管約束下的自應(yīng)力輕骨料混凝土的膨脹性能進(jìn)行了試驗(yàn)研究。在此基礎(chǔ)上，，對(duì)6個(gè)自應(yīng)力輕骨料鋼管混凝土中長(zhǎng)柱開展了承載下的火災(zāi)響應(yīng)及火災(zāi)后軸壓力學(xué)性能試驗(yàn)研究，并用Marc有限元軟件對(duì)其火災(zāi)下的溫度場(chǎng)進(jìn)行了模擬。為了對(duì)比分析，制作了18個(gè)自應(yīng)力輕骨料鋼管混凝土短柱和24個(gè)鋼纖維增強(qiáng)輕骨料鋼管混凝土短柱，并分別開展了常溫及火災(zāi)后軸壓力學(xué)性能的試驗(yàn)研究。其中受火條件考慮了700℃受火（1.5h）和900℃受火（1.5h）兩種情況。基于試驗(yàn)結(jié)果，對(duì)各組鋼纖維輕骨料鋼管混凝土柱及自應(yīng)力輕骨料鋼管混凝土柱的實(shí)驗(yàn)現(xiàn)象、破壞形態(tài)進(jìn)行了觀測(cè)與分析。得到了各組試件受火后的荷載-位移曲線及荷載-應(yīng)變曲線，分析了各個(gè)參數(shù)對(duì)火災(zāi)后自應(yīng)力輕骨料鋼管混凝土柱及鋼纖維輕骨料鋼管混凝土柱的承載能力和變形能力的影響。同時(shí)對(duì)試件常溫下的極限承載力及火災(zāi)后的剩余承載力進(jìn)行了分析比較。 試驗(yàn)結(jié)果表明，在軸壓力作用下的自應(yīng)力輕骨料鋼管混凝土中長(zhǎng)柱火災(zāi)后剩余承載力下降幅度與無(wú)荷載作用的輕骨料鋼管混凝土短柱火災(zāi)后剩余承載力下降幅度相差不大。輕骨料鋼管混凝土柱火災(zāi)后軸壓破壞形態(tài)與常溫下的情況基本一致。根據(jù)常溫試件和火災(zāi)后試件的試驗(yàn)結(jié)果，鋼纖維的摻量和膨脹劑的摻量對(duì)輕骨料鋼管混凝土短柱承載力均有一定的影響。隨著試件含鋼率的增加，鋼纖維和膨脹劑的增強(qiáng)效果逐漸減弱。初始自應(yīng)力和鋼纖維摻量對(duì)火災(zāi)后輕骨料鋼管混凝土柱的承載力提高作用效果隨火災(zāi)溫度的升高而降低。根據(jù)試驗(yàn)結(jié)果，進(jìn)一步分析了火災(zāi)溫度對(duì)剩余承載力的影響規(guī)律，并基于普通鋼管混凝土設(shè)計(jì)規(guī)程，提出了考慮自應(yīng)力影響的輕骨料鋼管混凝土短柱承載力計(jì)算方法。給出了考慮含鋼率影響的鋼纖維輕骨料鋼管混凝土短柱承載力修正系數(shù)，經(jīng)修正后的公式可用于常溫下鋼纖維輕骨料鋼管混凝土柱承載力計(jì)算。
[Abstract]:At present, many researches have been carried out on the fire resistance of ordinary concrete-filled steel tubular columns at home and abroad, but less on the fire behavior of concrete filled steel tubular columns with light aggregate. Especially, the research on fire response and post-fire mechanical properties of steel fiber reinforced lightweight aggregate concrete filled steel tube columns is weaker. In this paper, two kinds of lightweight aggregate concrete filled steel tube columns with different properties were made by adding a certain amount of expansive agent and steel fiber into concrete with shale ceramsite as coarse aggregate. A series of light aggregate concrete filled steel tube columns are studied on the fire resistance of concrete filled steel tube columns. The addition of steel fiber can effectively restrain the development of micro-cracks in core concrete and improve the mechanical properties of lightweight aggregate concrete filled with steel tube, while the addition of expansive agent can improve the stiffness of lightweight aggregate concrete to a certain extent. Therefore, the research on self-stress and mechanical properties of steel fiber reinforced lightweight aggregate concrete filled steel tube has important theoretical significance and engineering application value. In this paper, the expansion behavior of self-stressed lightweight aggregate concrete under steel pipe restraint is studied by using the steel content and the content of expansive agent as the varying parameters. On this basis, the fire response and axial compressive mechanical properties of six medium length columns with self-stressed lightweight concrete-filled steel tube (CFST) under load are studied. The temperature field under fire is simulated by Marc finite element software. In order to compare and analyze, 18 self-stressed lightweight concrete filled steel tube columns and 24 steel fiber reinforced lightweight concrete filled steel tube columns were made, and the mechanical properties of axial compression at room temperature and after fire were studied respectively. The fire conditions include 700 鈩

本文編號(hào)：2430126