BEHAVIOUR OF PROFILED STEEL SHEET DRY BOARD SYSTEM. W. Hamidon Badaruzzaman, E. Ahmed and A. Khalim Rashid

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1 CIB W89 BEIJING INTERNATIONAL CONFERENCE, OCTOBER, 1996 BEHAVIOUR OF PROFILED STEEL SHEET DRY BOARD SYSTEM W. Hamidon Badaruzzaman, E. Ahmed and A. Khalim Rashid The National University of Malaysia, Selangor, Malaysia. SUMMARY This paper reviews the overall structural behaviour of an innovative composite panel namely 'Profiled Steel Sheet Dry Board (PSSDB) panel'. The PSSDB panels are formed by attaching dryboards to a core of profiled steel sheeting using mechanical connectors. The panels can be exploited for a variety of structural purposes. It is very light and therefore easily transportable, and can be erected quickly by unskilled labour. It will be shown in this paper that the structural performance of the PSSDB panels when used as floors, walls, and folded plate roof structures are having considerable potential. A review of research works in the three major areas described above will be the main focus of this paper. KEYWORDS: Profiled steel sheet; Dryboard; Composite; Lightweight INTRODUCTION The profiled steel sheeting dryboard panel is a structural system consisting of profiled steel sheeting compositely connected to dry boards by simple mechanical connectors. Figure 1 shows the profiled steel sheet/dryboard system. The PSSDB system is an innovative form of construction conceived originally by Wright and Evans [1]. The original research programme [1,2] concentrated upon the development of the system as flooring units in domestic and low-rise buildings. Further research works have been conducted to study the behaviour of the system as walling [3,4] and roofing units in buildings [5]. The system carries the out of plane bending and shear when used as flooring units. It acts as a membrane carrying the in plane deformation and shear when used as wall units. It carries both the in plane and out of plane bending and shear in the case of folded plate roof units. Figure 1 Profiled steel sheet dryboard system.

2 STRUCTURAL BEHAVIOUR The structural behaviour of the proposed PSSDB panel must be fully understood before its potential can be realised. The panel is used as load bearing structural members as described earlier. The behaviour of such panel with regard to its structural performance against out of plane bending and shear, and in plane deformation and shear are reviewed in this paper. PSSDB as Flooring Unit As a flooring unit, PSSDB panel carries the out-of plane bending and shear, either along its major axis (as in most cases), or along its minor axis. An investigation, supported by a SERC grant [1,2], was conducted to study the behaviour of the panel subjected to out of plane bending along its major axis. It was shown that the bending stiffness of the bare profiled steel sheet could be increased by approximately 30% when the dry boarding was attached using fixings at 300mm centres along each trough of the profile. On the basis of Newmark's [6] partial interaction method, an analysis was proposed and gave good agreement with the experimental tests. In a comparison with traditional timber joist flooring, the efficiency of the system was demonstrated. It was demonstrated that the PSSDB system could be designed to be 100mm less deep than the traditional system for a 4m span floor carrying domestic loading. A recent study conducted by Ehsan [7,12,13,14], into the out of plane bending behaviour of PSSDB panels constructed from different profiled steel sheeting and dryboards to those used in references [1] and [2] above, confirmed the findings of previous researchers. Photo in Figure 2 shows the test arrangement for a PSSDB floor panel. Figure 2 Test arrangement for PSSDB floor panel. Figure 3 shows the load-deflection characteristic for three typical PSSDB panels [7]. It is observed that the initial load-deflection response is linear and elastic till just before failure. The mode of failure has been identified as buckling of the upper flanges of the profiled steel sheeting. The bending stiffnesses of the PSSDB floor panels are dependent on the dryboard and sheeting types and thicknesses, and also on the screw types and spacing. As a summary, it was found that for all tests, the theoretical results are more conservative compared to experimental results. This can be seen from Figure 4, which shows a comparison between the theoretical and experimental stiffnesses. The experimental

3 work and reasons behind the slight deviation in results are given in detail in references [7] and [12]. Figure 3 Load-deflection relationship of PSSDB floor panels with 100mm spacing of connectors Figure 4 Comparison of theoretical and experimental stiffnesses PSSDB as Walling Unit Research works have been carried out at Strathclyde University [3,4] to study the behaviour of PSSDB panel as a walling unit. Composite panels, comprising of steel sheeting with 12mm and 18mm thick chipboards have been tested in the laboratory. The specimens were tested under both pure axial and eccentric loadings. All tests showed similar failure sequences. At first, the screwed connection distort, then local buckling in weak wide compression flanges occurs with dial gauges rotating continuously, indicating overall buckling is progressing. Finally, the load starts to drop till the PSSDB panels failed. It was shown that the axial load capacity of walls comprising slender profiled steel sheeting could be improved by using the PSSDB system. The board component was found to carry a certain proportion of the applied load. Due to the attachment of the boards, an increased lateral bending stiffness can be achieved that prevent early buckling of the walls. Theoretical analysis of PSSDB walling unit as a load bearing element has also been carried out [4]. Based upon simple interaction theory, a computer program was written, and column interaction curves were prepared. It was observed that the experimental results at ultimate load are always greater than the theoretical results. This is due to the plasticity of the steel sheeting which was not taken into account during the theoretical investigation. More details of the work conducted along this line can be found in references [3] and [4]. PSSDB as Folded Plate Roof Member Research work has been conducted at Cardiff University [5,15,16,17,18] to study the behaviour of structures formed by assembling a number of PSSDB panels into a folded plate configuration. The use of PSSDB system in single pitched roofs will have the significant advantage of removing the skeletal internal bracing of normal roof truss construction. The roof structure derives its strength and stiffness from the folded plate action arising from the

4 structural geometry. Figure 5 shows a photo, of a full scale folded plate model that has been tested by Wan Badaruzzaman [5,15]. The PSSDB system, because of the addition of timber boarding, has an improved in plane shear and minor axis bending stiffness compared to bare profiled steel sheeting alone. This makes it more suitable for use as a component within a folded plate structure. Figure 5 Full scale folded plate roof structure model. To predict the structural behaviour of the proposed system, a computer program [5,17] based on orthotropic folded plate approach [5,16] had been developed. The program is able to predict closely results obtained for deflections from the full scale tests [5,18], as indicated in Figure 6 for one of the tests that has been conducted. It can be concluded that a folded plate structure constructed from the PSSDB system is structurally efficient and has considerable potential. Further tests are at present being carried out by the authors to fully study the behaviour of such structure till failure [8]. CONCLUSION This paper has described the overall structural behaviour of an innovative composite panel, namely the PSSDB panel. A literature review of all the up to date research works has been conducted. It can be concluded that the PSSDB panel has considerable potential as a replacement to traditional flooring, walling, and roofing system in building constructions. The key characteristics of the proposed system are its lighweight, the ease with which it can be transported, and the fact that it can be assembled and erected rapidly with unskilled labour. There are many structures in which the characteristics are very beneficial.

5 Figure 6 Comparison of results for deflections of full scale folded plate roof model. As flooring units it can provide slender sections for mezzanine and domestic floors. As walls, it provides excellent axial, bending and racking resistance, while as folded plate roofs, the system is efficient in resisting both combined in and out of plane actions. The removal of roof trusses and support is advantageous in speeding up construction of domestic houses and emergency shelters for disaster relief [9,10,11]. ACKNOWLEDGEMENT The authors would like to express sincere gratitude to the Universiti Kebangsan Malaysia for providing the fund for the research conducted as reported in this paper, BHP Lysaght (Malaysia) Sdn Bhd, and Hume Building Panels Research Centre Sdn Bhd for the supply of testing materials and moral support throughout the research work. REFERENCES 1. Wright, H.D., and Evans, H.R. Profiled steel sheeting for the replacement of timber flooring in building renovation, SERC Grant GR/D/76875, Wright, H.D., Evans, H.R., and Burt, C.A. Profiled steel sheet/dry board composite floors. The Structural Engineers, 1989, Vol 67, No. 7, pp Jekale,W. The Behaviour of Composite Structures Formed from Profiled Steel Sheeting and Dry Boarding. Thesis submitted in partial fulfillment for MSc degree, University of Strathclyde, UK, Mengesha, W.J. Composite Profiled Steel Sheet/Dryboard Panels. Thesis submitted in partial fulfillment for MSc degree, University of Strathclyde, UK, Wan Hamidon Badaruzzaman. The Behaviour of Profiled Steel Sheet/Dryboard System. Ph.D Thesis, University of Wales, College of Cardiff, UK, Newmark, N.M., Siess, C.P., and Viest, I.M. Tests and analysis of composite beams with incomplete interaction. Proc. Society for Experimental Stress Analysis, 1951, 9(1), pp Ehsan Ahmed. Behaviour of Profiled Steel Sheet Dryboard Panel. Thesis Submitted in fulfillment of MSc degree, University Kebangsaan Malaysia, Selangor, Malaysia, Wan Hamidon Badaruzzaman. Behaviour of PSSDB panels. Research Grant UKM FK 03/95, James, R. Temporary disaster relief housing. BEng dissertation, University of Wales, Cardiff, Manesha, An experimental study of a rapidly erected shelter system. Thesis submitted in partial fulfilment for MSc

6 degree, University of Wales, Cardiff, UK, Wood, C. Temporary disaster relief housing. BEng dissertation, University of Wales, Cardiff, Wan Hamidon Badaruzzaman, Ehsan Ahmed, and Khalim Rashid. Out of plane bending stiffness along the major axis of PSSDB composite floor panels. Has been accepted for publication in the Journal of Engineering, the National University of Malaysia, Bangi, Ehsan Ahmed, Wan Hamidon Badaruzzaman, and Khalim Rashid. A simplified elastic composite floor section analysis with incomplete interaction. Has been accepted for publication in the Journal of Engineering, the National University of Malaysia, Bangi, Wan Hamidon Badaruzzaman, Ehsan Ahmed, and Khalim Rashid. Composite Partial Interaction of Profiled Steel Sheeting/Dry Board Floor Analysis Subject to Transcerse Loading. Has been accepted for presentation and publication in the proceeding of CIB Beijing International Conference, October, Wan Hamidon Badaruzzaman, and Evans, H.R. An experimental study and elasticity approach of the behaviour of orthotropic folded plate roof models. To be published. 16. Wan Hamidon Badaruzzaman, and Evans, H.R. An experimental study and elasticity approach of the behaviour of orthotropic folded plate roof models. To be published. 17. Wan Hamidon Badaruzzaman, and Evans, H.R. Analysis of Orthotropic Folded Plate by Elasticity Method. To be published. 18. Wan Hamidon Badaruzzaman, and Evans, H.R. Computer solution for structures containing orthotropic and isotropic plates. To be published.