Test 37 - Plastic Analysis of Steel Structures

Question 1 ప్రశ్న 1

Which statement most accurately describes plastic analysis of a steel structure?

A It determines collapse by allowing redistribution of bending moments as plastic hinges form, provided equilibrium, ductility and stability requirements are satisfied B It assumes that every section remains perfectly elastic until the complete structure suddenly fractures C It ignores equilibrium after the first section reaches yield stress D It is applicable only to axially loaded columns and not to beams or frames

Question 2 ప్రశ్న 2

Which statement correctly distinguishes ordinary elastic analysis from plastic analysis of a ductile steel beam or frame?

A Elastic analysis generally limits behaviour by an elastic stress distribution, whereas plastic analysis can utilize moment redistribution up to formation of a collapse mechanism B Plastic analysis assumes stresses are always proportional to strain throughout the entire loading history C Elastic analysis permits unlimited rotation at constant plastic moment D There is no difference between elastic first yield and plastic structural collapse

Question 3 ప్రశ్న 3

For a homogeneous steel section subjected to pure bending, which expressions correctly represent the first-yield moment My and the fully plastic moment Mp?

A My = fyZe and Mp = fyZp B My = fyZp and Mp = fyZe C My = EZe and Mp = EZp D My = fyA and Mp = fyI

Question 4 ప్రశ్న 4

For a homogeneous cross-section subjected only to bending and having equal yield stress in tension and compression, where is the plastic neutral axis located?

A At an axis that divides the cross-sectional area into equal areas in tension and compression B Always at the extreme compression fibre C Always at the elastic centroid irrespective of section asymmetry D At an axis that divides the second moment of area into two equal parts

Question 5 ప్రశ్న 5

A solid rectangular steel section is 100 mm wide and 200 mm deep. If fy = 250 MPa, what is its first-yield moment My about the centroidal axis parallel to the width?

A 83.3 kN·m B 125.0 kN·m C 166.7 kN·m D 250.0 kN·m

Question 6 ప్రశ్న 6

What is the plastic section modulus Zp of a solid rectangular section 100 mm wide and 200 mm deep about its centroidal axis parallel to the width?

A 0.50 × 10^6 mm^3 B 0.667 × 10^6 mm^3 C 1.00 × 10^6 mm^3 D 1.50 × 10^6 mm^3

Question 7 ప్రశ్న 7

What is the plastic shape factor Mp/My = Zp/Ze for a solid rectangular cross-section?

A 1.00 B 1.125 C 1.50 D 2.00

Question 8 ప్రశ్న 8

For the 100 mm × 200 mm rectangular section with fy = 250 MPa and Zp = 1.00 × 10^6 mm^3, what is its nominal plastic moment Mp?

A 166.7 kN·m B 200.0 kN·m C 250.0 kN·m D 375.0 kN·m

Question 9 ప్రశ్న 9

A steel section has elastic section modulus Ze = 800 × 10^3 mm^3 and plastic section modulus Zp = 920 × 10^3 mm^3. What are its shape factor and percentage increase of Mp over My?

A 1.05 and 5 percent B 1.15 and 15 percent C 1.20 and 20 percent D 1.50 and 50 percent

Question 10 ప్రశ్న 10

What is a plastic hinge in the idealized plastic analysis of a steel structure?

A A yielded zone capable of significant inelastic rotation while sustaining approximately the plastic moment B A physical pin installed in the member before loading C A section at which bending moment must remain zero D A brittle fracture plane that cannot rotate

Question 11 ప్రశ్న 11

Under the IS 800 section-classification framework, what section class is required at a location where a plastic hinge is relied upon for a plastic collapse mechanism?

A Class 1 plastic section B Class 2 compact section only C Class 3 semi-compact section D Class 4 slender section

Question 12 ప్రశ్న 12

For a structure having degree of static indeterminacy r, how many additional plastic hinges are generally required to convert it into a complete collapse mechanism, assuming a single independent mechanism is involved?

A r B r + 1 C 2r D 2r + 1

Question 13 ప్రశ్న 13

A simply supported beam of span 8 m has a constant plastic moment capacity Mp = 200 kN·m and carries a central point load P. What is the collapse load?

A 50 kN B 100 kN C 200 kN D 400 kN

Question 14 ప్రశ్న 14

A simply supported beam of span 10 m carries a point load P located 4 m from the left support and 6 m from the right support. If Mp = 240 kN·m, what is the collapse load?

A 80 kN B 100 kN C 120 kN D 160 kN

Question 15 ప్రశ్న 15

A simply supported beam of span 6 m has constant plastic moment capacity Mp = 180 kN·m and carries a uniformly distributed load w over the full span. What is the collapse load intensity?

A 20 kN/m B 30 kN/m C 40 kN/m D 80 kN/m

Question 16 ప్రశ్న 16

A fixed-ended beam of span 8 m has the same plastic moment capacity Mp = 200 kN·m in positive and negative bending and carries a point load at midspan. What is the plastic collapse load?

A 100 kN B 150 kN C 200 kN D 300 kN

Question 17 ప్రశ్న 17

A fixed-ended beam of span 6 m has constant plastic moment capacity Mp = 180 kN·m and carries a uniformly distributed load over the full span. What is the collapse load intensity?

A 40 kN/m B 60 kN/m C 80 kN/m D 120 kN/m

Question 18 ప్రశ్న 18

A propped cantilever of span 8 m has constant plastic moment capacity Mp = 200 kN·m and carries a central point load. What is the collapse load?

A 100 kN B 150 kN C 200 kN D 300 kN

Question 19 ప్రశ్న 19

A cantilever beam of span 3 m has constant plastic moment capacity Mp = 180 kN·m and carries a point load at its free end. What is the collapse load?

A 30 kN B 60 kN C 90 kN D 180 kN

Question 20 ప్రశ్న 20

A single-bay, single-storey portal frame has rigid beam-column joints, both column bases fixed, column height h = 4 m and equal plastic moment capacity Mp = 180 kN·m at all four potential sway-hinge locations. Neglect gravity loads and second-order effects. What horizontal load H at beam level produces the simple sway collapse mechanism?

A 90 kN B 135 kN C 180 kN D 360 kN

Question 21 ప్రశ్న 21

What principle is used in the virtual-work method for determining the collapse load of an assumed plastic mechanism?

A External work done by the collapse loads during a compatible virtual displacement equals the internal work dissipated at the plastic hinges B External work is always twice the internal work C Only elastic strain energy before first yield is considered D Plastic-hinge rotations are ignored

Question 22 ప్రశ్న 22

Which statement correctly describes the lower-bound or static theorem of plastic collapse?

A Any bending-moment distribution that satisfies equilibrium and boundary conditions and nowhere exceeds the plastic moment provides a safe lower bound to the true collapse load B Any assumed collapse mechanism always gives a lower bound C The structure must violate equilibrium to establish a lower bound D A lower-bound solution requires every possible section to be at Mp simultaneously

Question 23 ప్రశ్న 23

Which statement correctly describes the upper-bound or kinematic theorem of plastic collapse?

A A kinematically admissible collapse mechanism evaluated by virtual work gives a collapse-load estimate that is not less than the true collapse load B Every kinematic mechanism gives a load lower than the true collapse load C A mechanism need not satisfy displacement compatibility D The theorem applies only before first yield

Question 24 ప్రశ్న 24

A lower-bound equilibrium solution proves that a frame can safely carry a load factor of 1.42, while the lowest kinematically admissible mechanism gives a collapse factor of 1.46. What can be concluded about the true plastic collapse factor?

A It must be less than 1.42 B It lies between 1.42 and 1.46 inclusive C It must be exactly 1.44 D It must exceed 1.46

Question 25 ప్రశ్న 25

Which set of material requirements is consistent with the IS 800 provisions for use of plastic analysis, unless adequate ductility is demonstrated by other permitted means?

A Yield stress not exceeding 450 MPa, tensile-to-yield strength ratio at least 1.2, adequate yield plateau and elongation, and strain-hardening capability B Any yield stress is acceptable even for a perfectly brittle steel C Tensile strength must be lower than yield strength D Elongation and ductility are irrelevant because only equilibrium matters

Question 26 ప్రశ్న 26

Which statement correctly describes the member and connection requirements at plastic-hinge regions in an IS 800 plastic analysis?

A Members and connections must permit the required plastic hinges and rotations to develop without premature local or lateral instability or connection failure B Connections may fail before the plastic hinges form because their behaviour does not affect collapse analysis C Lateral restraint is unnecessary at plastic hinges because the section has already yielded D A semi-compact section is always sufficient at every plastic-hinge location

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