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装配式地下粮仓钢-混组合仓壁节点力学性能有限元分析

Finite element analysis on mechanical properties of joint in precast steel plate-concrete composite wall of underground granary

  • 摘要: 地下粮仓是构建绿色储粮新体系的重要技术支撑,结合工程实际提出了一种新型装配式钢板-混凝土组合地下粮仓。为了建立适用于装配式地下粮仓的有限元模型以模拟分析组合仓壁节点的力学性能,并通过有限元分析指导组合仓壁节点力学性能试验的开展,基于工程设计的钢板-混凝土组合仓壁及连接接头,采用ANSYS软件建立了仓壁及其节点1∶1足尺试件的有限元模型,模拟分析了无接头、有接头试件的受弯和受压性能,并开展仓壁节点抗弯、抗压试验对有限元模拟结果进行验证分析。结果表明:试件的钢板和混凝土由栓钉连接为一体,试验过程中二者未见剥离可共同工作,建模时钢板和混凝土共用结点以及接头钢板之间假定为刚性连接是适用的;同类试件挠度曲线、轴压荷载-位移曲线的试验结果与其有限元模拟结果基本一致,无接头试件和有接头试件弯曲跨中位移、轴压最大位移的试验值与对应的模拟值,相对误差分别在4%和10%以内;试验过程中试件未发生明显破坏和过大变形,应力总体上未超过工程设计允许值,数值模拟结果精度满足工程所需;有接头试件力学性能与无接头试件相近,设计的仓壁及其节点是安全、可靠的,其结构计算可以采用等同原理,即该装配式仓壁可等效为现浇一体的无接头仓壁。建立的仓壁节点有限元模型适用于新型装配式地下粮仓,研究结果为装配式地下粮仓有限元建模分析、结构计算提供参考,为组合仓壁节点试验的开展提供指导。

     

    Abstract: Abstract: The underground granary is an important technical development for building a new system of green grain storage. Compared to the overground granary, the underground granary can make full use of the underground space, which shows significant advantages such as low temperature, loss reduction, eco-friendly environment, land saving, energy saving and safety in grain storage. Currently, such technology is one of the important research interests in the food industry. A new type of underground granary consisting of precast steel plate-concrete composite walls was proposed, and the corresponding mechanical properties of its wall and joints were studied for guiding the design of it. Firstly, two different finite element models of the two pieces of precast steel plate-concrete composite walls with different connecting modes were established with ANSYS software. One model is assumed that the walls connect with a joint, which is modeled as a short steel plate, and another is assumed to be weld together directly without introducing a joint. Their bending and compression properties were simulated and analyzed. Also, in the finite element simulation, Solid 185 element was used to model the concrete part, Shell 63 element was used to model steel plates, and the rigid connection was assumed by arranging common nodes between adjacent elements on the interface of concrete and steel plate. Secondly, the corresponding joint experiments were carried out to verify the simulation results. In the experiment, the steel plate and concrete are connected by bolts in each piece of composite wall. The steel plates of the two composite walls are connected by welding them together with a short connecting steel plate, and thus their connections are assumed to be rigid as well. Practically, in order to simplify the finite element models, the effects of bolts and rebar reinforcements in the real steel plate-concrete composite wall were represented by rigid connection assumptions. Numerical results showed that, for the case of empty granary, which means no internal pressure was applied on the internal surface of the composite wall, the stress concentration occur in the steel plate-concrete composite wall under the external soil and water pressure, but the maximum stress not exceeded the design value, so the prefabricated steel plate-concrete composite wall is safe. During the tests, the separation of steel plate and concrete in each specimen not happened and they worked well as an entire element. Besides, the connecting plate between the two precast steel plate-concrete composite walls looked reliable and no obvious crack damage or excessive deformation. All welding lines kept intact. The numerical results of the maximum deflection along the whole span of the jointless and jointed specimens were 0.7mm and 0.57mm, respectively, and the latter was 18.6% smaller than the former. The numerical predictions of the maximum axial displacement of the jointless and jointed specimens were 1.03mm and 1.01mm, respectively, with a slight difference of 1.94%. Besides, it is observed that the difference between the numerical results and the experimental results was no more than 4% and 10% for the jointless and jointed specimens, respectively. From the comparison, it is concluded that the experimental results are basically same as the finite element results and the established finite element model is verified. Also, the results indicate that the assumption of rigid joint between the two steel plate-concrete composite walls is reasonable. More importantly, it is found that the mechanical properties of the steel plate-concrete composite wall with joint connection are similar to those without joint. Thus, in the practical engineering, the steel plate-concrete composite walls for the underground granary can be mechanically equivalent to the steel plate-concrete composite wall without joint connection. It provides guidance for the design and test of composite wall joint.

     

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