预制混凝土夹芯墙连接件受力性能及墙体热工性能研究

发布时间：2018-08-11 12:07

【摘要】：预制混凝土夹芯墙满足建筑节能和住宅产业化的要求,具有广阔的应用前景,然而国内研究处于起步阶段,需要开展进一步研究工作来支持其在实际工程中的应用。连接件是预制混凝土夹芯墙中保证内叶、外叶和保温层协同工作的关键部件,其力学性能关系到墙体的安全性和耐久性,而预制混凝土夹芯外墙的热工性能优劣直接决定着预制装配式建筑的保温隔热性能和建筑能耗。为此,本文针对预制装配式混凝土夹芯墙体系,展开了内、外叶间复合式连接件的受力性能与夹芯墙的热工性能试验及数值模拟研究。首先,对设置复合式连接件的预制混凝土夹芯墙体进行了单侧拉拔、单侧剪切、双侧拉拔、双侧剪切共计84个试件的试验研究工作,获得了复合式连接件的抗拉和抗剪受力性能,并就连接件与钢筋网片的位置关系对极限承载力的影响进行了分析。结果表明:单个连接件的拉拔承载力均值为12.1k N~27.3k N,抗剪承载力均值为15.5k N~18.8k N,具有较大的安全储备;拉拔破坏和剪切破坏均属于脆性破坏;连接件与分布钢筋的位置关系对极限承载力几乎没有影响,但外叶墙钢筋网片能够延缓连接件十字叉的拔出过程;基于锥形体拉拔破坏模式,提出了适用于复合式连接件的拉拔承载力计算公式,并得到了试验结果的验证;提出了适用于单侧和双侧剪切的受力模型,基于ABAQUS对连接件穿心钢筋的剪切性能进行了有限元分析,得到了实验结果的验证。其次,展开对预制混凝土夹芯墙体热工性能的试验研究。根据夹芯保温层厚度、保温层材料、墙体中连接件位置的不同设计并制作了4片夹芯墙,采用热箱-热流计法对墙体的传热系数进行了实测,并与各墙体传热系数的理论计算值进行了对比,结果表明:连接件位置形成的热桥,导致墙体平均传热系数增大约32.4%;保温层厚度与保温层材料对墙体传热系数有显著的影响;墙体传热系数理论值均明显小于试验结果,这是由于连接件使墙体传热过程由一维变成了多维,基于一维传热假设的传统理论计算方法不再适用于本文墙体传热系数的计算。最后,基于通用有限元软件ANSYS对设置有复合式连接件的预制混凝土夹芯保温墙体进行了数值模拟,分析了连接件的热桥效应,在有限元模型得到试验结果验证的基础上,对影响墙体传热系数的各项因素包括各材料导热系数、保温层厚度、连接件布置间距等展开扩大参数分析,结果显示:传热系数的有限元结果与试验均值相对误差在30%之内,且由数值模拟获得的各试验墙体内、外表面温度、内表面热流密度、传热系数变化规律与试验结果完全相同,证实本文有限元模型能够模拟带有连接件墙体的传热过程;在复合式连接件及附近,温度急剧变化,热流密度增大非常明显,热桥效应显著;连接件穿心钢筋的外裹尼龙使墙体传热系数降低约15.4%,但增加外裹尼龙的厚度对墙体热工性能的改善作用有限;穿心钢筋、混凝土、保温层以及外裹尼龙材料的导热系数皆对墙体传热系数有较大影响,其中穿心钢筋的导热系数越大,墙体传热系数越高,但影响程度逐渐减弱,当穿心钢筋导热系数较低时(λ_steel≤20 W/(m2?K)),外裹尼龙效果不明显;在保证结构安全性的前提下,增大连接件布置间距和减小穿心钢筋直径均可大幅度提高墙体热工性能。
[Abstract]:Prefabricated concrete sandwich wall meets the requirements of building energy conservation and residential industrialization, and has broad application prospects. However, domestic research is still in its infancy, and further research is needed to support its application in practical projects. The mechanical properties of the components are related to the safety and durability of the wall, and the thermal performance of the prefabricated concrete sandwich wall directly determines the thermal insulation performance and building energy consumption of the prefabricated assembly building. Firstly, 84 specimens of prefabricated concrete sandwich wall with composite connectors were tested and studied, including unilateral pull-out, unilateral shear, bilateral pull-out and bilateral shear. The tensile and shear properties of composite connectors were obtained. The results show that the average pull-out bearing capacity of a single connector is 12.1kN~27.3kN, and the average shear bearing capacity is 15.5kN~18.8kN, which has a large safety reserve. The pull-out failure and shear failure are brittle failure. It has little effect on the ultimate bearing capacity, but the steel mesh of outer leaf wall can delay the pull-out process of the connector cross. Based on the conical pull-out failure mode, a formula for calculating the pull-out bearing capacity of composite connectors is proposed and verified by the test results. Based on ABAQUS, the finite element analysis of the shear performance of the connector core-piercing steel bar is carried out, and the experimental results are verified. Secondly, the experimental study on the thermal performance of the precast concrete sandwich wall is carried out. The results show that the average heat transfer coefficient of the wall increases by about 32.4% due to the heat bridge formed by the connecting parts, and the thickness of the insulation layer and the material of the insulation layer have a significant effect on the heat transfer coefficient of the wall. The theoretical values are obviously smaller than the experimental results, because the connection changes the heat transfer process from one-dimensional to multi-dimensional, the traditional theoretical calculation method based on the one-dimensional heat transfer assumption is no longer applicable to the calculation of the heat transfer coefficient of the wall in this paper. Finally, based on the general finite element software ANSYS, the precast concrete sandwich protection with composite connection is carried out. The thermal bridge effect of the connector is analyzed by numerical simulation. On the basis of the experimental results of the finite element model, the factors affecting the heat transfer coefficient of the wall, including the thermal conductivity of each material, the thickness of the insulation layer, the spacing between the connectors and so on, are analyzed. The results show that the finite element results of the heat transfer coefficient are satisfactory. The relative error is within 30% of the test mean, and the variation law of the temperature, heat flux and heat transfer coefficient of the inner and outer surfaces of the test walls obtained by numerical simulation is identical with the test results, which confirms that the finite element model can simulate the heat transfer process of the wall with connectors; the temperature changes sharply in and near the composite connectors. The heat transfer coefficient of the wall decreases by about 15.4% with the increase of the thickness of the outer nylon, but the improvement of the thermal performance of the wall is limited with the increase of the thickness of the outer nylon. The greater the thermal conductivity of the steel bar through the core, the higher the heat transfer coefficient of the wall, but the degree of influence is gradually weakened. When the thermal conductivity of the steel bar through the core is lower (lambda_steel < 20 W /(m2? K)), the effect of nylon coating is not obvious; on the premise of ensuring the structural safety, increasing the spacing of connectors and reducing the diameter of the steel bar through the core can be significant. The thermal performance of the wall is improved.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU111.4;TU37

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