Procedures

Question 1

What are the steps to create a Magnel Diagram?

Answer 1

Find 4 limiting strengths if not given
Use Ztop and Zbot to find a trial section if not given
Calculate beam s/w
Find line origins with +_Z/A
Guess e and use equations for second points

Question 2

What is a useful assumption for the CSA of a trial section of prestressed concrete?

Answer 2

Breadth:Height ratio is 1:2

Question 3

What is the equation for Z of a concrete beam?

Answer 3

b(h^2)/6

Question 4

When do you apply design factors for a rigid steel frame?

Answer 4

After all the forces on the lowest beams have been found in SLS

Question 5

What are the steps of finding design forces in a rigid steel frame?

Answer 5

Draw a dimensioned frame
Draw a loaded frame to SLS
Calculate vertical loads, moments and reactions
Calculate wind loads, moments and reactions
Sum the forces in the beams, outer and inner columns applying design factors

Question 6

What are the moments caused by the vertical forces in columns of a rigid frame?

Answer 6

Outer: M/2
Inner: 0

Question 7

What are the steps for sizing components of a plate girder?

Answer 7

Draw SFD and BMD
Use max BM to find Wply
Use chart to find y
Estimate flange area
Choose a flange thickness and check the unattached length/thickness ratio is suitable to the Eurocode

Question 8

What is the equation for estimating area of a plate girder flange?

Answer 8

Med/(y*fy)

Question 9

What are the steps to check stiffener spacing for a plate girder?

Answer 9

First put stiffeners under all point loads
Calculate max shear capacity
Find a/d and d/tw of each span
Use chart to find chi
Multiply chi by Vmax and check against SFD
If not satisfied, divide actual shear by Vmax for Chi required and find a from chart

Question 10

What are the steps to find the cable profile for a prestressed concrete beam?

Answer 10

Use P=10^6/P from Magnel Diagram
Calculate Z/A and Z/P
Draw a bending moment diagram and find quarter moments for transfer and service loads
Use data sheet equations to find the values of e at each quarter span and plot
Remember -ve e is above the neutral axis

Question 11

What are the steps for finding the critical stresses at the outer faces of a composite section?

Answer 11

Calculate concrete conversion factor
Draw a diagram
Find the areas and use to find the neutral axis
Calculate I
Make a table of loads and moments
Calculate stresses from associated moments

Question 12

What is the concrete contribution to I when n/a is in the beam?

Answer 12

bd^3/12 + bdz^2
b is the reduced ‘steel’ width

Question 13

What is the steel contribution to I?

Answer 13

Iyy from data sheet + Av*z^2

Question 14

What is the concrete contribution to I when n/a is in the slab?

Answer 14

(bx^3)/3

Question 15

How do you design stud layout for a composite section?

Answer 15

Multiply steel strength by beam area (Fst) for capacity
Calculate P for stud and concrete
Divide steel beam capacity by min P
Divide beam length by number of studs for centres

Question 16

How do you size welds for an end plate on a beam web?

Answer 16

Find the hypotenuse of shear and axial forces in the beam, each divided by web depth x 2
Compare this capacity to data sheets

Question 17

How are beam forces divided among bolts in a rigid end plate?

Answer 17

Top 4 bolts take upper flange moment
Lower 2 bolts take shear in web

Question 18

How do you find the moment in each flange for fixed end plates?

Answer 18

Total moment divided by distance between flange centres

Question 19

What is the equation for moment at a quarter span?

Answer 19

3wL^2/32

Question 20

What are the steps for checking ULS moment capacity of a composite section?

Answer 20

Find d, h and beff
Choose a suitable beam
Make a table of loads
Compare Fcc and Fst
Find neutral axis
Multiply Fst by z for Mrd

Question 21

What is the capacity of a shear stud?

Answer 21

(0.8 fv pi d^2)/5

Question 22

What is the shear capacity of concrete against studs?

Answer 22

(0.29 fv^2 sqrt(fck Ec))/1.25