CE-801 Design of Steel Structures - Nov 2023 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 10 Marks
   aDesign a built-up column consisting of two channels placed back-to-back to carry an axial factored load of $1500\text{ kN}$. Length of the column is $6\text{m}$ and the column is restrained in position but not in direction at both ends. Provide single lacing system with bolted connection.
   How to answer

   • Select suitable channel section for factored load and effective length
   • Check slenderness ratio and design compressive strength per IS 800-2007
   • Design single lacing system: slenderness, flat size, spacing
   • Design bolted end connections and check spacing requirements
2. 4 Marks
   bIllustrate the different elements of plate girder.
   How to answer

   • Define plate girder and its use for large spans
   • List elements: flanges, web, stiffeners, splices, connections
   • Illustrate cross-section and longitudinal view with neat sketch
3. 10 Marks
   aDesign a suitable slab base for a column section ISHB 200@ $365.9\text{N/m}$ supporting an axial load of $500\text{ kN}$. The base plate is to rest on a concrete pedestal of M20 grade concrete. The load is transferred to the base plate by welded connection.
   How to answer

   • Calculate required base plate area from bearing strength of M20 concrete
   • Select base plate size and check projection
   • Determine plate thickness from bending of overhang
   • Design welded connection of ISHB 200 column to base plate
4. 4 Marks
   bExplain block shear failure.
   How to answer

   • Define block shear failure
   • Explain tension and shear failure planes
   • Mention IS 800-2007 strength equations for block shear
5. 5 Marks
   aExplain the factors effecting strength of tension members.
   How to answer

   • Define tension member strength: gross, net, block shear
   • Discuss slenderness, shear lag, holes, connection eccentricity
   • Discuss material properties and end conditions
6. 9 Marks
   bDesign a tension member to carry factored load of $400\text{ kN}$ connected to shorter leg back-to-back. Length of member is $3\text{ m}$.
   How to answer

   • Calculate required net area for $400\text{ kN}$ factored load
   • Select double angle back-to-back on shorter leg
   • Check tensile strength and slenderness
   • Design connection details
7. 10 Marks
   aDesign a purlin on a sloping roof truss with the dead load of $0.15\text{ kN/m}^2$, a live load of $2.5\text{kN/m}^2$ and a wind load of $0.6\text{ kN/m}^2$ (suction) The purlins are $1.8\text{m}$ center-to center and a span of $3.8\text{m}$, simply supported on a rafter at a slope of $20^{\circ}$.
   How to answer

   • Calculate dead, live and wind loads per metre on purlin
   • Resolve loads about major and minor axes for $20^{\circ}$ slope
   • Calculate bending moments for $3.8\text{ m}$ simply supported span
   • Select suitable channel/angle purlin section and check
8. 4 Marks
   bWith the help of suitable diagram, explain the concept of shear lag.
   How to answer

   • Define shear lag with non-uniform stress distribution
   • Show connected vs unconnected legs with diagram
   • Explain reduction factor and IS 800 provisions
9. 9 Marks
   aA tie member of a roof truss consisting of an angle section ISA $75 \times 75 \times 10$ of Fe 410 grade, is welded to a $10\text{mm}$ thick gusset plate. Design a weld to transmit a load equal to full strength of the member. Assume shop welding.
   How to answer

   • Calculate full tensile strength of ISA $75\times 75\times 10$, Fe 410
   • Determine required weld strength for shop welding
   • Design longitudinal and transverse weld length/size
   • Check eccentricity and detailing
10. 5 Marks
    bDistinguish between laterally restrained and unrestrained beams.
    How to answer

    • Define laterally restrained beam
    • Define laterally unrestrained beam and lateral-torsional buckling
    • Compare design strength, effective length and applications in table
11. 5 Marks
    aDistinguish between working stress design and limit state design of steel structures.
    How to answer

    • State assumptions of working stress method
    • State principles of limit state method
    • Compare safety, load factors, economy in points
12. 9 Marks
    bA column section ISHB 250@ $500.3\text{ N/m}$ carries an axial load of $600\text{ kN}$. Design the column splices.
    How to answer

    • Note column section properties for ISHB 250
    • Design splice plates for axial load $600\text{ kN}$
    • Check bolts/welds for splice connection
    • Detail splice location and sketch
13. 5 Marks
    aExplain the purpose of lug angles in tension member connection.
    How to answer

    • Define lug angle
    • Explain reduction of shear lag and connection length
    • Explain when lug angles are required with sketch
14. 9 Marks
    bDetermine the design tensile strength of the plate $200 \times 10\text{mm}$ with the holes as shown below if the yield strength and ultimate strength of steel are $250\text{MPa}$ and $410\text{MPa}$. M20 bolts and $10\text{mm}$ thick gusset plates are used.
    How to answer

    • Calculate hole diameter for M20 bolts and net areas at sections
    • Calculate gross section yielding strength with $f_y=250\text{MPa}$
    • Calculate net section rupture and block shear with $f_u=410\text{MPa}$
    • Report minimum as design tensile strength
15. 14 Marks
    Write a short notes on any two:

    1. i)Different types of weld
    2. ii)Sketch different types of bolted connections
    3. iii)Lap joint and their types
    4. iv)Roof truss and their types
    How to answer

    • Select any two topics from i)-iv)
    • Give definition, classification and key points for each
    • Add neat sketches/examples and IS code relevance