StructuralComponents7.0

A study of rigid frames behaviour and a computational tool prototype for the early design of mid-rise buildings

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Abstract

During the early stages of the construction process of a building, the potential impact of design decisions is at its greatest. One of the reasons is the lack of computational tools at these stages. The main objective of this research project was the expansion of StructuralComponents by the development of a parametric real-time computational tool prototype to quickly determine the feasibility of mid-rise buildings designs with rigid frames as stability members. A study of rigid frames behaviour was performed to define a range of applicability of the existing analytical representation and to develop two new methods to analytically represent rigid frames behaviour: a correction method for the shear beam representation and a method based on the Timoshenko beam theory. To allow for vertical connections of different rigid frame geometries, an analytical method to consider a different stiffness along the height was developed. The results showed that the analytical shear beam representation of rigid frames has a reduced range of applicability for parametric purposes. This reduced applicability is due to the combined shear and bending behaviour. The correction method follows from the prediction of the error when using the shear beam representation. In addition to the correction of the shear beam representation, the prediction of the error was defined as a parameter to classify the behaviour of a rigid frame as a shear, flexural or combined type. Both, the applicability range and the correction method are based on analytical and numerical comparisons, as well as the performed validations. The implemented software comprises Maplesoft to get the analytical solutions and Grasshopper with Karamba3D (which contains the finite element solver) to get the numerical solutions. The method based on the Timoshenko beam theory comes from the theoretical derivations of a serial system that takes into account both, bending and shear deformations. It was found that it is more appropriate to analytically represent the general behaviour of rigid frames with the Timoshenko beam theory and by additionally considering a different stiffness calculation for the ground floor. Also, it was shown that the vertical connections of rigid frame geometries can be addressed with the calculation of an analytical solution for each different geometry along the height. Both analytical approaches, the Timoshenko beam representation and the method for vertical connections were implemented in the tool prototype. Such a tool consists of a calculation method to assess the structural performance of a building by the simultaneous structural analysis of every rigid frame subjected to a lateral load. The three main characteristics of the tool prototype are the parametric adaptability, the instantaneous display of results and the stacking “Lego-type” connection between components. The validations in this research project showed that the proposed and implemented methods are suitable for preliminary design stages because the error for the most unfavourable geometric configurations resulted in less than 15 percent. It is recommended to conduct further research and tool development. In so doing, more informed decisions can be made during the preliminary design stages.