負(fù)載下外包鋼筋混凝土加固軸壓鋼柱的承載性能研究
發(fā)布時間：2019-05-23 23:08
【摘要】：外包鋼筋混凝土加固鋼柱近年來得到越來越廣泛的應(yīng)用。這種加固方式解決了鋼結(jié)構(gòu)的防火、防腐問題,提高了純鋼柱的整體、局部穩(wěn)定性,但我國鋼結(jié)構(gòu)加固規(guī)范并沒有給出這種加固方式的計(jì)算方法和構(gòu)造要求(打栓釘、加強(qiáng)柱腳)。世界各國(地區(qū))規(guī)范中型鋼混凝土正截面承載力的計(jì)算模式主要有四種：基于數(shù)值計(jì)算結(jié)果的經(jīng)驗(yàn)公式、將型鋼視為等效的鋼筋,按照混凝土柱的承載力計(jì)算模式計(jì)算、將混凝土轉(zhuǎn)化為等效型鋼,按照純鋼柱的承載力計(jì)算模式計(jì)算以及采用強(qiáng)度疊加理論的型鋼混凝土柱計(jì)算方法。強(qiáng)度疊加理論簡單,安全,并且符合我國設(shè)計(jì)人員的習(xí)慣。比較了各國(各地區(qū))規(guī)范中型鋼保護(hù)層厚度、鋼筋保護(hù)層厚度、型鋼和鋼筋間距、型鋼含鋼率、縱筋直徑、間距、配筋率,箍筋直徑、加密區(qū)間距、配筋率,翼緣寬厚比、腹板高厚比等構(gòu)造要求,為我國新鋼結(jié)構(gòu)加固規(guī)范提供建議。開展軸心壓力下的外包混凝土加固鋼柱的試驗(yàn)研究,根據(jù)試驗(yàn)數(shù)據(jù),分析了疊合柱截面的應(yīng)力分布,以及疊合柱的傳力方式。后澆混凝土與內(nèi)部型鋼共同工作機(jī)理研究,加固形成的型鋼混凝土疊合柱是二次受力結(jié)構(gòu),加固前原結(jié)構(gòu)未卸載的荷載為第一次受力；后澆鋼筋混凝土在加固后并未立即產(chǎn)生應(yīng)力重分布,而是共同分擔(dān)第二次受力新增的荷載。第二次受力過程中,后澆鋼筋混凝土中的應(yīng)變滯后于原來鋼柱的應(yīng)變,鋼柱的累計(jì)應(yīng)變始終高于后澆鋼筋混凝土部分的應(yīng)變。鋼柱達(dá)到極限狀態(tài)時,后澆鋼筋混凝土部分的應(yīng)變還很低,材料強(qiáng)度沒有得到充分發(fā)揮,應(yīng)予以折減。疊合柱中原鋼柱和后澆混凝土能否共同工作,取決于接觸面的構(gòu)造處理和施工做法,如加焊栓釘。運(yùn)用Abaqus對加固后疊合柱進(jìn)行模擬分析,混凝土材料采用塑性損傷本構(gòu),鋼筋選擇等向強(qiáng)化本構(gòu),鋼筋內(nèi)置區(qū)域植入混凝土之中,原鋼柱與混凝土之間的粘結(jié)滑移采用型鋼混凝土粘結(jié)滑移公式,為了準(zhǔn)確模擬組合板的二階段制造和二次受力,引入了生死單元。初應(yīng)力使得外包鋼筋混凝土加固的鋼柱荷載-變形位移曲線后移,軸力集中于鋼骨,初應(yīng)力系數(shù)和型鋼材料強(qiáng)度對其承載力折減影響顯著。建立基于疊加原理的外包鋼筋混凝土加固鋼柱的承載力計(jì)算公式以及折減系數(shù),與試驗(yàn)值吻合較好。
[Abstract]:Steel columns strengthened with reinforced concrete have been more and more widely used in recent years. This reinforcement method solves the problem of fire prevention and anticorrosion of steel structure, and improves the overall and local stability of pure steel column. However, the calculation method and structural requirements of this reinforcement method are not given in the reinforcement code of steel structure in our country. Strengthen the foot of the column). There are four main calculation modes of normal section bearing capacity of medium-sized steel concrete in codes all over the world: based on the empirical formula of numerical calculation results, section steel is regarded as equivalent steel bar, and the bearing capacity of concrete columns is calculated according to the calculation model of bearing capacity of concrete columns. The concrete is transformed into equivalent section steel, and the bearing capacity of pure steel column is calculated according to the calculation mode of bearing capacity of pure steel column and the calculation method of steel reinforced concrete column based on strength superposition theory. The theory of strength superposition is simple, safe and in line with the habits of designers in our country. The thickness of medium steel protective layer, the thickness of steel bar protective layer, the spacing between section steel and steel bar, the steel content, longitudinal bar diameter, spacing, reinforcement ratio, hoop diameter, reinforcement area spacing, reinforcement ratio and flange width to thickness ratio are compared in different countries (regions). The structural requirements such as web height to thickness ratio provide suggestions for the reinforcement code of new steel structures in China. The experimental study on steel columns strengthened with external concrete under axial pressure is carried out. according to the test data, the stress distribution of the section of the composite columns and the force transfer mode of the composite columns are analyzed. The working mechanism of post-pouring concrete and internal section steel is studied. The steel reinforced concrete composite columns formed by reinforcement are secondary stress structures, and the ununloaded load of the original structure before reinforcement is the first load. The stress redistribution of post-pouring reinforced concrete does not occur immediately after reinforcement, but the additional load added to the second force is shared. In the second stress process, the strain in the post-cast reinforced concrete lags behind that of the original steel column, and the cumulative strain of the steel column is always higher than that of the post-cast reinforced concrete part. When the steel column reaches the limit state, the strain of the post-cast reinforced concrete part is still very low, and the material strength has not been brought into full play, so it should be reduced. Whether the original steel column and post-pouring concrete can work together in the superimposed column depends on the structural treatment and construction method of the contact surface, such as adding welding bolt nail. Abaqus is used to simulate and analyze the superimposed columns after reinforcement. The plastic damage constitution is adopted in the concrete material, the isotropic strengthening constitution is selected for the steel bar, and the built-in area of the steel bar is embedded in the concrete. The bond slip between the original steel column and concrete adopts the bond slip formula of section steel concrete. In order to accurately simulate the two-stage manufacture and secondary force of the composite slab, the life and death element is introduced. The initial stress makes the load-deformation displacement curve of the steel column strengthened with reinforced concrete move back, and the axial force is concentrated on the steel bone. The initial stress coefficient and the strength of the section steel material have a significant effect on the reduction of the bearing capacity of the steel column. The calculation formula and reduction coefficient of bearing capacity of steel columns strengthened with reinforced concrete based on superposition principle are established, which are in good agreement with the experimental values.
【學(xué)位授予單位】：沈陽建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU391
本文編號：2484318
[Abstract]:Steel columns strengthened with reinforced concrete have been more and more widely used in recent years. This reinforcement method solves the problem of fire prevention and anticorrosion of steel structure, and improves the overall and local stability of pure steel column. However, the calculation method and structural requirements of this reinforcement method are not given in the reinforcement code of steel structure in our country. Strengthen the foot of the column). There are four main calculation modes of normal section bearing capacity of medium-sized steel concrete in codes all over the world: based on the empirical formula of numerical calculation results, section steel is regarded as equivalent steel bar, and the bearing capacity of concrete columns is calculated according to the calculation model of bearing capacity of concrete columns. The concrete is transformed into equivalent section steel, and the bearing capacity of pure steel column is calculated according to the calculation mode of bearing capacity of pure steel column and the calculation method of steel reinforced concrete column based on strength superposition theory. The theory of strength superposition is simple, safe and in line with the habits of designers in our country. The thickness of medium steel protective layer, the thickness of steel bar protective layer, the spacing between section steel and steel bar, the steel content, longitudinal bar diameter, spacing, reinforcement ratio, hoop diameter, reinforcement area spacing, reinforcement ratio and flange width to thickness ratio are compared in different countries (regions). The structural requirements such as web height to thickness ratio provide suggestions for the reinforcement code of new steel structures in China. The experimental study on steel columns strengthened with external concrete under axial pressure is carried out. according to the test data, the stress distribution of the section of the composite columns and the force transfer mode of the composite columns are analyzed. The working mechanism of post-pouring concrete and internal section steel is studied. The steel reinforced concrete composite columns formed by reinforcement are secondary stress structures, and the ununloaded load of the original structure before reinforcement is the first load. The stress redistribution of post-pouring reinforced concrete does not occur immediately after reinforcement, but the additional load added to the second force is shared. In the second stress process, the strain in the post-cast reinforced concrete lags behind that of the original steel column, and the cumulative strain of the steel column is always higher than that of the post-cast reinforced concrete part. When the steel column reaches the limit state, the strain of the post-cast reinforced concrete part is still very low, and the material strength has not been brought into full play, so it should be reduced. Whether the original steel column and post-pouring concrete can work together in the superimposed column depends on the structural treatment and construction method of the contact surface, such as adding welding bolt nail. Abaqus is used to simulate and analyze the superimposed columns after reinforcement. The plastic damage constitution is adopted in the concrete material, the isotropic strengthening constitution is selected for the steel bar, and the built-in area of the steel bar is embedded in the concrete. The bond slip between the original steel column and concrete adopts the bond slip formula of section steel concrete. In order to accurately simulate the two-stage manufacture and secondary force of the composite slab, the life and death element is introduced. The initial stress makes the load-deformation displacement curve of the steel column strengthened with reinforced concrete move back, and the axial force is concentrated on the steel bone. The initial stress coefficient and the strength of the section steel material have a significant effect on the reduction of the bearing capacity of the steel column. The calculation formula and reduction coefficient of bearing capacity of steel columns strengthened with reinforced concrete based on superposition principle are established, which are in good agreement with the experimental values.
【學(xué)位授予單位】：沈陽建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU391
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，本文編號：2484318
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