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Sections. WORKSHEET 9b. to answer just click on the button or image related to the answer. let's go !!. that it is strong enough. that it won’t bend. a. that it is stiff enough. a and b. b and c. b. d. e. c. Question 1a. when we want to check a beam.

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  1. Sections WORKSHEET 9b to answer just click on the button or image related to the answer let's go !!

  2. that it is strong enough that it won’t bend a that it is stiff enough a and b b and c b d e c Question 1a when we want to check a beam what do we need to check for?

  3. a the span and support types the loading conditions on the beam the material, shape and dimensions of the beam the maximum bending moment the moment of inertia and section modulus b d e c f a, b and c Question 1b when we want to check a beam what do we need to know to start?

  4. the maximum allowable bending stress a the Modulus of Elasticity the maximum allowable deflection whether it is elastic, plastic or brittle all the above b d e c f a, bandc Question 1c when we want to check a beam what else do we need to know?

  5. what do we do first? a calculate the load on a joist find the tributary area for a joist calculate the section modulus of a joist b c Question 2a we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m

  6. what is the tributary area for a joist? a 2.16 m2 4.32 m2 3.6 m2 b c Question 2b we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m

  7. what is the total load on a joist? a 4.104 kN 4.104 kPa 3.24 kN b c Question 2c we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist)

  8. a the maximum deflection the maximum bending moment the maximum bending stress b c Question 2d we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) to check the strength what do we need to find?

  9. a the maximum deflection the maximum bending moment the section modulus a and c b d c Question 2e we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) to find the maximum stress what do we need?

  10. a a uniformly distributed load a point load b Question 2f we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) to find the maximum BM we need to know the type of load is is the load?

  11. a 6.65 kNm 1.85 kNm 6.65 kN 3.70 kNm b d c Question 2g we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) what is the maximum BM?

  12. 83.3 x 103 mm3 333.3 x 103 mm4 333.3 x 103 mm3 a b c Question 2h we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) what is the Section Modulus? (remember Question 3b in the earlier Tutorial)

  13. 5.6 MPa 4.1 MPa 1.62 MPa a b c Question 2i we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) what is the maximum bending stress in a joist?

  14. yes maybe no a b c Question 2j we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) Given that we have found the maximum bending stress in the beam to be 5. 6 MPa if softwood F8 grade is capable of taking 8 MPa, is the beam strong enough ?

  15. the modulus of elasticity the deflection the moment of inertia a b c Question 2k we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) to check whether the beam is stiff enough, what do we need to find ?

  16. what is the deflection ? 84.0 mm 12.5 mm 8.4 mm a b c Question 2l we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) given that the deflection for a simply supported beam with a UDL is 5 WL3 / 384 E I and the Modulus of Elasticity of F8 timber is 9000 MPa

  17. no maybe yes a b c Question 2m we want to check the floor joists in the upper floor of a house. Given that they are 200 x 50 mm softwood joists @ 600 mm centres spanning 3.6 m and that we have a live load of 1.5 kPa and a dead load of 0.4 kPa (including the self-weight of the joist) given that the maximum allowable deflection for the beam is Span / 300 is the beam stiff enough?

  18. enough ! next question a Great Start When checking a beam, we need to check it for both strength and stiffness, i.e. that it doesn’t break and that it doesn’t deflect too much

  19. let me try again let me out of here Sorry all beams bend to some degree

  20. let me try again let me out of here uummhh!! partly but that’s not all

  21. enough ! next question You Bewdy ! We must start with some known information. This includes: the span, the support type (simple, pin, etc), the total load on the beam and the properties of the beam (material, shape and dimensions)

  22. let me try again let me out of here uummhh!! partly but that’s not all

  23. let me try again let me out of here No, that's not it! We will have to work the max BM out, but to do that we need to know certain things first

  24. let me try again let me out of here No, that's not it! We will have to work them out, but to do that we need to know certain things first

  25. enough ! next question yes! yes! yes! in addition to the span & support type, the loading conditions, the material, shape and dimensions, the max bending stress, the Modulus of Elasticity and the max deflection are the things that we have to be given from tables and codes

  26. let me try again let me out of here uummhh!! partly but that’s not all

  27. let me try again let me out of here Oh my gosh!! Why would we want to know whether it’s elastic, plastic or brittle In order to check a beam for strength and stiffness?

  28. enough ! next question right on! before we can calculate the total load on a beam, we have to determine what area produces the load on the beam

  29. let me try again let me out of here No, that's not it! Before we can work out the total load we need to know something first

  30. let me try again let me out of here Well, possibly We could but we would probably do something more fundamental first

  31. tributary area 200 x 50 mm timber joists @ 600mm crs 3600 600 600 600 enough ! next question Fantastic tributary area = 3.6 x 0.6 = 2.16 m2

  32. tributary area 200 x 50 mm timber joists @ 600mm crs 3600 600 600 600 let me try again let me out of here Not right !! what is the length of the joist? What is the distance between joists?

  33. enough ! next question Yeaaahh! tributary area = 2.16 m2 total distributed load = 1.9 kPa total load on joist = 2.16 x 1.9 = 4.104 kN (remember: 1 kPa = 1 kN/m2. So if you multiply kPa x m2 you get kN)

  34. let me try again let me out of here it's enough to make one cry We are talking about the TOTAL LOAD What are the units of a load (force)? (remember: 1 kPa = 1 kN/m2. So if you multiply kPa x m2 you get kN)

  35. let me try again let me out of here Uhhhh ??? How did you get that? What’s the tributary area? What’s the load per sq m?

  36. enough ! next question Good Work! to check strength, we need to compare the actual stress in the beam to the maximum allowable stress

  37. let me try again let me out of here Sorry! we will need that but that’s not what we really need to find. What is it that we need to do in order to check the strength of a beam?

  38. let me try again let me out of here No! No! No! What is it that we need to do in order to check the strength of a beam?

  39. enough ! next question Yipee !! Yes! The formula is f = M / Z So we need both M and Z to find f

  40. let me try again let me out of here uummhh!! partly correct. Remember the formula for stress in a beam. What else do we need?

  41. Don’t guess let me try again let me out of here No, No, No !! what has deflection to do with strength?

  42. next question enough ! Yipee !! you’ve got it !! The load is carried over the whole length of the beam

  43. let me try again let me out of here No, No, No !! is the load at one point only? Or over the whole length of the beam?

  44. enough ! next question yes, yes, yes !! for a simply supported, UDL beam, Max BM = WL / 8 (W = Total Load) = 4.104 x 3.6 / 8 = 1.85 kNm

  45. let me try again let me out of here No, No, No !! we did say UDL not point load What’s the formula for the maximum BM for a simply supported beam with a UDL? it’s not WL / 4

  46. let me try again let me out of here Sorry but, No !! What’s the formula for the maximum BM for a simply supported beam with a UDL?

  47. let me try again let me out of here No, No, No !! What’s the formula for the maximum BM for a simply supported beam with a UDL? What are the units for moments?

  48. enough ! next question Brilliant !! Z = bd2 / 6 = 50 x 2002 / 6 = 5 x 10 x 4 x 104 / 6 = 2000 / 6 x 103 = 333.3 x 103 mm3

  49. how many times? let me try again let me out of here Oh, my Goodness!! what’s the depth? What’s the width? repeat after me … a beam is deeper than wide, …. a beam is deeper ….

  50. what are the units for Section Modulus? let me try again let me out of here No! No! No! look at the formula! Z = bd2 / 6 mm x mm2 = ?

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