Week 1 Challenge

CHALLENGE 1

QUESTION 1 ANSWER

Truss A is more efficient than truss B

Truss A is pratt truss and truss B is Howe truss

In pratt truss the diagonal members are arranged so that they only develop tensile forces. As such, they can be designed to

resist axial tension only, avoiding the need for a compression buckling analysis. The vertical members in a Pratt truss develop

compression forces. This means they will typically be more robust and capable of resisting buckling.

Howe trusses are essentially the opposite of Pratt trusses in terms of geometry. In fact, looking at a Pratt truss upside-down

will visualize a Howe truss of sorts. The entire structure is still relatively the same, but the diagonal braces are now occupying

the opposite or the unoccupied joints. This switch in position of the diagonal members has a very important effect structurally.

Pratt trusses have their vertical members in compression and diagonal members in tension upon the application of gravity

loads at the joints of the top chord. For Howe trusses, the reverse becomes true as diagonal members are now in

compression, while the vertical loads are in tension.

QUESTION 2 ANSWER

QUESTION 3 ANSWER

a)MOI ALONG Iz=18341333.3333 mm4

MOI ALONG ly=1843244.9123 mm4

Weight per meter= 23.84kg/m

b)MOI ALONG Iz=5442066666.6667 mm4

MOI ALONG ly=135042666.6667 mm4

Weight per meter= 204.1 kg/m

c)MOI ALONG Iz=18540000 mm4

MOI ALONG ly=1420000 mm4

Weight per meter= 74.34 kg/m

d)MOI ALONG Iz=64180000 mm4

MOI ALONG ly=81630000 mm4

Weight per meter= 74.34 kg/m

QUESTION 4 ANSWER

Floor width = 10kN/m²

^{Tributary width of exterior girder = 0.5(0+8) = 4m}

^{Tributary width of interior girder = 0.5(8+8) = 8m}

^{Tributary width of exterior beam = 0.5(0+2) = 1m}

^{Tributary width of interior beam = 0.5(2+2) = 2m}

^{Load on beam = tributary width x floor load}

^{Load on exterior girder = 4 x 10 = 40Kn/m}

^{Load on beam interior girder = 8 x 10 = 80 Kn/m}

^{Load on beam exterior beam = 1 x 10 = 10Kn/m}

^{Load on beam interior beam = 2 x 10 = 20 Kn/m}

QUESTION 5 ANSWER

Given, Initial total length= 2000 m

Temperature difference = 60 degrees

Coefficient of Thermal expansion of steel = 12x10^-6/°C

Length difference = 2000*60*12x10^-6 =1.44m

Total length = 2001.44 m