The Modified Force-Density Method for Form-Finding of Membrane Structures

다국어 초록 (Multilingual Abstract)

In the force-density method, the value of force-density can only be determined after several trial calculations by now, which often depend on the experience of the researcher. This makes the process of form-finding inefficient and sometimes even invalid. In this manuscript, the disadvantage of the above-mentioned method was overcome through the following two modifications: membrane stress and cable tension were used as initial conditions instead of assuming the value of force-density (i.e. the quantitative relationships between the membrane stress, the cable tension and the force-density are established), and the unbalanced force of each node was used to control the error. This significantly reduced the number of trial calculations required. Several complex cases showing the validity and efficiency of the algorithm. A form-finding experiment of the membrane structure using Fluotop T2 was conducted in order to verify the modified force-density method. The experimental model was a saddle-shaped tensile membrane with 4 cable boundaries, 4 supports and a plane size of 4 m×4 m. The following three parameters were selected for measurement: (a) cable strains, (b) membrane strains and (c) coordinates of several testing points on the membrane surface in two states of the model, one called the unrestrained state and the other called the equilibrium state. These three parameters were compared among the results of the experiment, numerical simulation and analytical methods.
We concluded that the modified force-density method was valid and can be used in the form-finding analysis for membrane structure engineering applications.

참고문헌 (Reference)

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