This study presents spatial vibration modelling of steel–concrete composite beams. Structures of this type are commonly used as elements of composite floors and primary carrying girders in bridge structures. Two-dimensional models used to date did not enable analysis of all eigenmodes, specifically torsional, flexural horizontal, and distortional. A discrete computational model was developed in the convention of the rigid finite element method, the so-called RFEM model. It was assumed that the concrete slab and the steel I-section would be modelled separately. This approach realistically reflects the actual performance of the connection, comprising studs connecting the concrete slab and the steel section. The model was used to analyse two steel–concrete composite beams with different connector spacings. The paper presents the results of experiments conducted on the two composite beams. Their dynamic characteristics, including frequency and vibration modes, were determined with impulse response methods. Based on experimental research, identification of connection parameters with substitute longitudinal moduli of elasticity of reinforced concrete was conducted. A comparison of experimental results with those calculated with the model confirmed their good agreement.

中文翻译：

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钢-混凝土组合梁的3D刚性有限元建模与参数辨识

这项研究提出了钢-混凝土组合梁的空间振动建模。这种类型的结构通常用作桥梁结构中复合地板和主要承载梁的元素。迄今为止，二维模型还不能分析所有本征模，特别是扭转，水平弯曲和变形。按照刚性有限元方法的惯例，开发了一个离散的计算模型，即所谓的RFEM模型。假定混凝土板和钢工字型截面将分别建模。这种方法真实地反映了连接的实际性能，包括将混凝土板和钢型材连接起来的螺柱。该模型用于分析两个具有不同连接器间距的钢-混凝土组合梁。本文介绍了在两个复合梁上进行的实验结果。用脉冲响应方法确定了它们的动态特性，包括频率和振动模式。在实验研究的基础上，进行了钢筋混凝土等效纵向弹性模量连接参数的识别。实验结果与模型计算结果的比较证实了它们的良好一致性。