CIV2503 - Projeto Estrutural I - Ação do Vento e Cálculo de Pressões

1 University of Southern Queensland Faculty of Health Engineering and Sciences Assignment 2 CIV2503 STRUCTURAL DESIGN I Due 29 September 2022 Marks 300 Note to students This assignment uses the last three digits denoted by x y z of your student ID number to individualise your design data You must use these three digits to obtain your own design data For example a student with ID number of 0060123456 will have x 4 y 5 z 6 Use 4 significant figures for midstep values and 3 significant figures for the value of a final answer Task 1 Wind action 75 marks Fig 1 Elevation views of the building doors not shown A portal frame factory building is to be constructed on an exposed site Terrain category 1 in Biloela QLD The building will be 48 m long 144 m wide 6 m high at the eaves and X 8x10 m high at the ridge Portal frames are spaced at 6m centres Number of people present in the building is estimated no more than 50 at any time There are no surrounding buildings and no adverse topography and the orientation of the building has not been finalised 1 Using AS 117022021 determine the site wind speed and design wind speed in strength limit state 15 marks 2 Then considering only cross wind direction ie normal to the ridge and in this particular case assuming there are one door with the area of Y 3 3y10 m2 on the windward wall and one door with the area of Z 4 4z10 m2 on one leeward wall carry out the following steps for strength limit state a Calculate and draw a map of design external pressures Pe 15 marks b Calculate critical design internal pressures Pi 15 marks c Determine the most critical net outward pressure for the roof ie uplift and the most critical outward and inward net pressures for the 48m long wall surfaces 15 marks 3 Finally use AS 117022011 R2016 to obtain the site wind speed and design wind speed for this building Evaluate the differences between these results and the ones obtained in step 1 and discuss the causes for the differences 15 marks See below for values of X Y and Z Permeability ratio of walls and roofs is 01 When having more than one opening all scenarios of the openings ie open or shut and their combinations should be considered to elect the most critical design cases Make other necessary assumptions and take Ka Kc K1 Kp 1 Example A student with xyz 456 will have X 8 410 84 m Y 3 3510 45 m2 Z 4 4610 64 m2 2 Task 2 Timber design 225 marks You are tasked to design a timber deck which will be used as an open dining space with tables and chairs not fixed for the public at the back of a twolevel restaurant building in Toowoomba Queensland Wheeled vehicle access is not available The deck is approximate 3X mm long 2Y mm wide and 30 m off the ground In reality handrails are needed to be in the exterior edges of the deck but their light weights are to be ignored for simplicity The timber deck is supported by a typical system of joists bearers posts hangers Joists support the flooring and span continuously over the three bearers which serve as the supports for the joist Each bearer is in turn supported by three posts and one wall hanger All designs are to be in accordance with AS 17201 2010 Timber Structures 1 Design Information Floor sheeting is 22 mm thick and nailed at 300mm centres Crosssectional dimensions of joists are 50 mm x 160 mm Crosssectional dimensions for bearers are 75 mm x 250 mm Crosssectional dimensions of post are 200 mm x 200 mm Imposed action refer AS11701 distributed only ignore concentrated action Long term deflection limit for both floor joist and bearer span300 Short term deflection limit i floor joist span300 ii bearer span250 Assume F17 stress graded unseasoned hardwood timber Blackbutt for all components floor sheeting joists bearers and posts Individual design data include i for bearer internal span X mm 4000 x10 ii for joist internal span Y mm 3000 y10 and spacing Z mm 400 z10 Example A student with xyz 456 will have X 4000 410 4040 mm Y 3000 510 3050 mm Z 400 610 460 mm Thus the footprint dimensions of the deck are approximately 3X 2Y 1212 m 61 m Fig 2 Timber deck viewed from underneath Interior post Main bearer Deck width 2 Y mm The side from restaurant Hangers used to connect bearers to a wall pinned connection Deck length 3 X mm Joists at Z mm centres 3 2 Design Task Determine the most critical strength design load combination largest for vertical loads G and Q using necessary load combinations as required by AS 11700 and produce line load diagrams for the following structural elements 1 a typical joist 15 marks 2 the main ie middle bearer 15 marks Then 3 Determine the critical design actions bending moment shear force and bearing force needed for the strength limit state design of a typical joist and the main bearer 30 marks 4 Carry out a design check for longterm deflections for the typical joist and the main bearer 15 marks 5 Carry out a design check for shortterm appearancerelated deflections for the typical joist and the main bearer 15 marks 6 Carry out a design check for bending moment shear and bearing capacities of the typical joist and the main bearer 75 marks 7 Determine the critical design axial load of one interior post and check its compressive strength 15 marks 8 Draw the plan and elevation of the final design with sufficient details as designed note hand or computer drawings are both fine provided each drawing is clear and shows necessary basics for construction 15 marks 9 Assume there is a need to lower the timber grade eg due to economical or supply issues to the lowest possible grade for the joists and bearers while still satisfying the basic strength and serviceability design requirements as checked in the previous steps Discuss where you will start from to enable a quick redesign process and summarise further steps bullet points are sufficient needed to achieve that purpose with the typical joist and the main bearer 30 marks Final note to students See overpage for some extra beam formulae in addition to those provided in module 2 of studybook FBD R₁ R₂ R₃ R₄ SFD BMD R₁ V₁ R₄ V₄ 0400wL R₂ R₃ 110wL V₂₁ V₃₂ 0500wL V₂₂ V₃₁ 0600wL M₁ M₅ at 0400L from R₁ or R₄ 0080wL² M₂ M₄ at R₂ or R₃ 0100wL² M₃ at mid centre span 0025wL² Maximum deflection Δmax at 0446L from R₁ or R₄ 00069wL⁴ EI FBD R₁ R₂ R₃ R₄ R₅ SFD BMD R₁ V₁ R₅ V₅ 0393wL R₂ R₄ 1143wL R₃ 0928wL V₂₁ V₄₂ 0607wL V₂₂ V₄₁ 0536wL V₃₁ V₃₂ 0464wL M₁ at 0393L from R₁ M₇ at 0393L from R₅ 00772wL² M₂ at R₂ 01071wL² M₃ at 0536L from R₂ M₅ at 0536L from R₄ 00364wL² M₄ at R₃ 00714wL² Maximum deflection Δmax at 0440L from R₁ and R₅ 00065wL⁴ EI