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Abstract
Ahmad Mohammed Ashraf Mohammed Alaa El-Din Eliwa ElGammal “Analysis of Green House Using Fiber Reinforced Polymer Cables”, master of Science dissertation, Ain Shams University, 2016.
This thesis presents a biconcave cable truss as a roofing system for green houses by using non-traditional cable materials. Not only traditional steel cables were used but also FRP cables namely: high-strength carbon FRP (CFRP), hybrid FRP cables such as basalt mixed with carbon with two different volume proportions 25% and 50% of carbon fiber called B/CFRP 25% and B/CFRP 50%, respectively. Also, another newly developed hybrid FRP cable formed by the hybridization of basalt and steel cables together with two volume proportions 20% and 30% called B/SFRP 20% and B/SFRP 30%, respectively. These hybrid cables have been tested for large scale cable stayed bridges and were deemed appropriate. Up to the author’s knowledge using FRP cables in cable trusses as roofing structure has never been studied.
Several parameters have been tested in this study to get a better understanding of the cable truss behavior. The output of each parameter was added to the next as an input. An excel based program was developed that linked excel with SAP2000 FE model this helped reduce the time needed for analysis and thus simplifying creating large number of analysis models and storing the results.
The parameters studied here are the effect of varying: the cable pretension as a function of yield strain, distributed loads (w), span-to-depth ratio with constant cable area, span-to-sag (L/s) ratio with span-to-camber (L/c) ratio, the optimum spacing between hangers and the number of elements between hangers, tieback angle with roller supports used instead of columns and finally tieback angle with vertical columns provided.
The major conclusions drawn from this study are as follows: (1) Cable truss stiffness is directly proportional to the pretension. (2) Cable truss stiffness is inversely proportional to the increase of w and (L/s). (3) Cable truss stiffness is inversely proportional to the
x
span-to-depth ratio. (4) Cable truss stiffness is directly proportional to L/c and inversely proportional to L/s. (5) The optimum span division for the cable truss studied is 12 (SpHang = L/12) while the number of elements needed between hangers (Nelem) is two for 60m span only otherwise, one element is enough. (6) Tieback angle (θ) is inversely proportional to both suspension (Asusp) and stabilizing (Astab) cable areas and directly proportional to tieback cable area (Atieback). (7) In the presence of columns, tieback angle (θ) has almost no effect on the forces generated in suspension and stabilizing cable. (8) Forces in the both tiebacks cables are directly proportional to the tieback angle (θ). (9) Using roller supports instead of columns severely underestimates the lower tieback and slightly overestimates the area of the suspension, stabilizing and upper tieback cable.
Keywords: Green House System, Fiber Reinforced Polymer (FRP), Biconcave Cable Truss Roofs, Suspension roofs, Geometric Nonlinearity, Fiber Reinforced Polymer (FRP) cables, Hybrid FRP composites, Visual Basic for Application (VBA), SAP2000 v19.2, Object Oriented Programming.