Performance of steel bolt connected industrialized building system subjected to hydrodynamic force with debris

Abstract

Several major floods have hit Malaysia within the last decades. In order to dampen the effects of the floods on communities’ different types of flood mitigation projects, mostly structural mitigation measures were carried out. While some of the measures have been successful in reducing the impact of the flooding, others were not that successful, leading to the collapse of building structures. Therefore, there is a need to concentrate on a recovery framework specially tailored towards building permanent settlements using a robust and cost-effective building system. An industrialized building system (IBS) has been proposed as one of the best solutions for rapidly building permanent settlements in flood-prone zones. However, the existing IBS is not designed to sustain the horizontal impact due to the debris carried by the flood. Thus, a new permanent settlement built in the aftermath of floods using the IBS will eventually be destroyed by the extreme impact of horizontal load in the next flood cycle. Previous studies on the behaviour and performance of the IBS subjected to horizontal impact are found to be lacking. Furthermore, the joint of an IBS is likely to be the weakest point and vulnerable to failure when subjected to the horizontal load. There is, therefore, the need to develop an improved IBS that is able to withstand the horizontal impact of the flood. Thus, this study aimed to investigate the performance and behaviour of steel bolt-connected IBS structures subjected to the sudden impact of hydrodynamic force with debris as well as the horizontal impact of the pendulum. Both dam-break tests and pendulum impact tests were simulated using Autodesk computational fluid dynamic (CFD) simulation and Autodesk simulation mechanical (nonlinear finite element analysis (NLFEA)) for optimizing the laboratory experimental work, respectively. A scale of 1:5 models (one-dimension (1D), two-dimensional (2D), and three-dimensional (3D)) were designed using Eurocode 2, developed, and constructed according to the Buckingham Pi Theorem and Similitude Theory and later tested in the laboratory. The three models which include the single column-footing, 2D IBS frame and 3D IBS platform were properly tested for the dam-break test with and without debris using 1 m, 2 m, and 3 m reservoir water height. These three models were also tested for the sudden impact of the pendulum. The result shows the percentage difference between experimental results and the CFD numerical simulation for the stress of the 3D platform is 12.87%, while the displacement difference is recorded as 0.09 cm. However, the bolt-connected IBS models resisted the highest hydrodynamic forces as compared to the estimated ones from FEMA P-646 and FEMA P-55. Hence, this assured the reliability of the bolt-connected IBS structure for real practice. Furthermore, results of the pendulum impact tests were verified with the published literatures and they showed a very good agreement. The results show that bolt-connection is more effective and contributes additional robustness to the IBS method. Moreover, bolt connection has proven to be effective in restricting damages from spreading to other structural components. The findings of this study are crucial to improving the current IBS method of construction. The study has also successfully enhanced understanding on the behaviour of debris impact on building structures and contributed new knowledge on debris impact in relation to the design code of practice.