CFRP加固混凝土箱梁日照溫度效應研究
發(fā)布時間：2018-11-22 10:10
【摘要】：在過去，國內(nèi)外研究者對加固混凝土結(jié)構(gòu)和構(gòu)件的力學及使用性能進行了大量的試驗研究與理論分析，已取得了豐碩的研究成果。由于應用廣泛的箱形梁橋出現(xiàn)得較晚，其加固實例還比較少，隨著時間的推移，早期修建的箱形梁橋?qū)⑾嗬^進入服役后期，加固問題必定會提到議事日程上來�；炷翞闊岬牟涣紝w，當外部環(huán)境出現(xiàn)較大的溫度變化時，混凝土結(jié)構(gòu)內(nèi)外會出現(xiàn)較大的溫差，從而導致較大溫差應力的出現(xiàn)。CFRP具有不同于混凝土的熱物性參數(shù)，因此CFRP的外部粘貼使原混凝土箱梁溫度場發(fā)生改變，同時當溫度變化時，CFRP-混凝土組合結(jié)構(gòu)中應力和變形等性能也將發(fā)生改變。故對CFRP加固混凝土箱梁的日照溫度效應的研究是非常有必要的。 本文進行了CFRP加固混凝土箱梁日照輻射作用下溫度場及溫度應力的試驗研究。制作了三片試驗梁，三片試驗梁均為鋼筋混凝土箱梁，具有相同的幾何尺寸，梁長3200mm，，橫截面高400mm，寬600mm，頂?shù)装搴穸染鶠?0mm，腹板厚60mm。在梁體L/4截面布置溫度傳感器，在跨中截面布置應變片。第一片梁不進行CFRP加固，對其余兩片梁進行不同方式的CFRP加固，分別為底面單層加固與U型加固。使用保溫材料，采用不同的遮陰方式模擬出三種不同的日照工況，同種工況測試三天，分別獲得了各試驗梁在不同工況作用下的溫度場及溫度應力數(shù)據(jù)，進行了初步的分析和探討。 使用ANSYS軟件對CFRP加固混凝土箱梁的日照溫度試驗進行有限元模擬，將實測數(shù)據(jù)作為初始條件，結(jié)合氣象學及大氣天文學的知識計算出邊界條件，以數(shù)組的形式施加給有限元模型，求得各試驗梁在不同時刻的溫度場；直接將已求得的溫度場施加給箱梁模型，計算出各試驗梁的溫度應力；將實測數(shù)據(jù)與有限元模擬的數(shù)據(jù)進行對比分析。 經(jīng)過對實測數(shù)據(jù)與有限元模擬數(shù)據(jù)的綜合分析最終得出；日照輻射作用下，箱梁頂板測點溫度最高值出現(xiàn)在下午15時~16時，而沿高度方向最大溫差出現(xiàn)在下午14時~16時。在箱梁同一截面，隨著高度的下降，溫度場時變規(guī)律有明顯的延遲現(xiàn)象，不同高度測點溫度時變曲線每天有兩次交叉點，此時基本不存在溫度梯度，箱梁整體溫度基本趨于一致；CFRP的粘貼改變了箱梁表面的太陽輻射吸收率，與同等條件下未粘貼CFRP的混凝土表面相比，其表面最高溫度高出4~5℃，最終導致了箱梁截面豎向溫差增大；不同日照輻射條件作用對CFRP加固混凝土箱梁的豎向溫度梯度存在一定的影響，當箱梁腹板位置直接承受日照輻射作用時，其豎向溫度梯度發(fā)生較大變化，尤其當腹板表面粘貼有CFRP時，這種影響體現(xiàn)的更加明顯；未經(jīng)CFRP加固的混凝土箱梁在日照溫度荷載作用下，其頂板大部受拉應力作用，部分受壓應力作用，底板基本受拉應力作用，最大拉應力出現(xiàn)在頂板下側(cè)。在頂面粘貼CFRP后，頂板承受溫度應力全為受壓，底板拉應力大于未加固箱梁的底板拉應力。
[Abstract]:In the past, the research and theoretical analysis of the mechanics and performance of the reinforced concrete structures and components by the researchers at home and abroad have made great achievements. Because of the late appearance of the wide box-beam bridge, the reinforcement of the box-beam bridge is less, and with the passage of time, the early-built box-beam bridge will enter the later stage of service, and the reinforcement problem will certainly be put on the agenda. The concrete is a hot bad conductor, and when the external environment has a large temperature change, a large temperature difference occurs inside and outside the concrete structure, leading to the occurrence of large temperature difference stress. The CFRP has a different thermal physical property than that of the concrete, so the external bonding of the CFRP changes the temperature field of the original concrete box girder, and the stress and deformation in the CFRP-concrete composite structure will also change when the temperature is changed. Therefore, it is necessary to study the solar temperature effect of the CFRP-reinforced concrete box girder. The experiment of temperature field and temperature stress under the action of the solar radiation of CFRP-reinforced concrete box girder is carried out in this paper The three test beams are produced. The three test beams are reinforced concrete box beams with the same geometrical dimensions. The beam length is 3200mm, the cross section is 400mm, the width is 600mm, the thickness of the top base plate is 80mm, and the thickness of the web is 60. mm. The temperature sensor is arranged in the section of the beam body L/ 4, and the cross-section arrangement shall be The first beam is not reinforced with CFRP, and the other two beams are reinforced with CFRP in different ways, which are single-layer and U-shaped on the bottom surface, respectively. The temperature field and temperature stress data of each test beam under different working conditions were obtained by using different shading methods, and the preliminary analysis was carried out. In this paper, the method of ANSYS software is used to simulate the sunshine temperature of the reinforced concrete box girder with CFRP, and the measured data is used as the initial condition, and the boundary condition is calculated by the knowledge of meteorology and atmospheric astronomy, and is applied to the form of an array. The finite element model is used to obtain the temperature field of each test beam at different time points, and the temperature field obtained is directly applied to the box girder model, and the temperature stress of each test beam is calculated; and the measured data and the data of the finite element simulation are The results of the comprehensive analysis of the measured data and the finite element simulation data are as follows: the maximum temperature of the top plate of the box girder under the action of solar radiation is at 15: 15 to 16, while the maximum temperature difference in the height direction appears below In the same section of box girder, the time-varying curve of temperature field has obvious delay in the same section of box girder. The temperature-varying curve of different height measuring points has two cross points every day. At this time, there is basically no temperature gradient, and the whole box girder the temperature is basically consistent; the bonding of the CFRP changes the solar radiation absorption rate on the surface of the box girder, and the maximum temperature of the surface of the concrete is 4-5 DEG C compared with the surface of the concrete which is not pasted with the CFRP under the same conditions, and finally the box girder The vertical temperature difference of the cross-section is increased; the effect of different sunshine radiation conditions on the vertical temperature gradient of the CFRP-reinforced concrete box girder has a certain effect, and when the position of the box girder web is directly subjected to the solar radiation action, the vertical temperature gradient of the box girder is greatly changed, especially when the surface of the web plate The effect of this effect is more obvious when the CFRP is pasted; under the action of the sunshine temperature load, the top plate of the reinforced concrete box girder under the action of sunshine temperature is subjected to tensile stress, the part of the top plate is subjected to compressive stress, the bottom plate is basically subjected to tensile stress, and the maximum tensile stress The force appears on the lower side of the top plate. After the CFRP is attached to the top surface, the top plate is subjected to temperature stress all under pressure, and the tensile stress of the bottom plate is greater than that of the non-reinforcement.
【學位授予單位】：蘭州交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U441.5;U445.72
本文編號：2348988
[Abstract]:In the past, the research and theoretical analysis of the mechanics and performance of the reinforced concrete structures and components by the researchers at home and abroad have made great achievements. Because of the late appearance of the wide box-beam bridge, the reinforcement of the box-beam bridge is less, and with the passage of time, the early-built box-beam bridge will enter the later stage of service, and the reinforcement problem will certainly be put on the agenda. The concrete is a hot bad conductor, and when the external environment has a large temperature change, a large temperature difference occurs inside and outside the concrete structure, leading to the occurrence of large temperature difference stress. The CFRP has a different thermal physical property than that of the concrete, so the external bonding of the CFRP changes the temperature field of the original concrete box girder, and the stress and deformation in the CFRP-concrete composite structure will also change when the temperature is changed. Therefore, it is necessary to study the solar temperature effect of the CFRP-reinforced concrete box girder. The experiment of temperature field and temperature stress under the action of the solar radiation of CFRP-reinforced concrete box girder is carried out in this paper The three test beams are produced. The three test beams are reinforced concrete box beams with the same geometrical dimensions. The beam length is 3200mm, the cross section is 400mm, the width is 600mm, the thickness of the top base plate is 80mm, and the thickness of the web is 60. mm. The temperature sensor is arranged in the section of the beam body L/ 4, and the cross-section arrangement shall be The first beam is not reinforced with CFRP, and the other two beams are reinforced with CFRP in different ways, which are single-layer and U-shaped on the bottom surface, respectively. The temperature field and temperature stress data of each test beam under different working conditions were obtained by using different shading methods, and the preliminary analysis was carried out. In this paper, the method of ANSYS software is used to simulate the sunshine temperature of the reinforced concrete box girder with CFRP, and the measured data is used as the initial condition, and the boundary condition is calculated by the knowledge of meteorology and atmospheric astronomy, and is applied to the form of an array. The finite element model is used to obtain the temperature field of each test beam at different time points, and the temperature field obtained is directly applied to the box girder model, and the temperature stress of each test beam is calculated; and the measured data and the data of the finite element simulation are The results of the comprehensive analysis of the measured data and the finite element simulation data are as follows: the maximum temperature of the top plate of the box girder under the action of solar radiation is at 15: 15 to 16, while the maximum temperature difference in the height direction appears below In the same section of box girder, the time-varying curve of temperature field has obvious delay in the same section of box girder. The temperature-varying curve of different height measuring points has two cross points every day. At this time, there is basically no temperature gradient, and the whole box girder the temperature is basically consistent; the bonding of the CFRP changes the solar radiation absorption rate on the surface of the box girder, and the maximum temperature of the surface of the concrete is 4-5 DEG C compared with the surface of the concrete which is not pasted with the CFRP under the same conditions, and finally the box girder The vertical temperature difference of the cross-section is increased; the effect of different sunshine radiation conditions on the vertical temperature gradient of the CFRP-reinforced concrete box girder has a certain effect, and when the position of the box girder web is directly subjected to the solar radiation action, the vertical temperature gradient of the box girder is greatly changed, especially when the surface of the web plate The effect of this effect is more obvious when the CFRP is pasted; under the action of the sunshine temperature load, the top plate of the reinforced concrete box girder under the action of sunshine temperature is subjected to tensile stress, the part of the top plate is subjected to compressive stress, the bottom plate is basically subjected to tensile stress, and the maximum tensile stress The force appears on the lower side of the top plate. After the CFRP is attached to the top surface, the top plate is subjected to temperature stress all under pressure, and the tensile stress of the bottom plate is greater than that of the non-reinforcement.
【學位授予單位】：蘭州交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U441.5;U445.72
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