(a) Pin-Pin P cr = (b) Fixed-Fixed P cr = (d) Fixed-Pin P cr =

Transcription

1 1. The most critical consideration in the design of rolled steel columns carrying axial loads is the (a) Percent elongation at yield and the net cross-sectional area (b) Critical bending strength and axial yield strength of the material (c) Compressive strength based on slenderness ratio and gross cross sectional area of the member (d) Buckling strength based on the net area of the section and percent elongation at ultimate load. In the case of structural steel sections, the Minimum ratio of thickness of elements in compression, in terms of their outstanding length is specified to prevent (a) Shear failure (b) local buckling (c) Bending failure (c) Tension failure 3. The effective length of a structural steel compression member of length L effectively held in position and restrained against rotation at one end but neither held in position nor restrained against rotation at the other end, is (a) L (b) 1.L (c).0l (d) 1.5L 4. Battening of columns shall be done where the columns are subjected to eccentric loading in the plane of battens 5. Batten plates are designed to resist moments and longitudinal forces arising due to transverse shear force. 6. A compression member has a Centre to centre length of 4.0m. It is fixed at one end and hinged at the other end. The effective length of the column is (a) 4.0m (b) 3.m (c).8m (d).6m 7. For a compression member having the same effective length about any cross-sectional axis, the most preferred section from the point of view of strength is (a) A box (b) A single angle (c) A circular tube (d) An I-section 8. In double-laced system of a built-up column, cross member perpendicular to the longitudinal axis of the column is not used. Page 1 of 14

2 9. Lacing bars are forced to share the axial load on the strut. 10. As far as practicable, the lacing system shall be varied throughout the length of the strut. 11. Single laced systems on opposite sides of the components shall be preferably be in mutually opposite directions, so that one is not the shadow of the other. 1. Rolled sections or tubes of equivalent strength may be used as lacing bars instead of flats. 13. Some steels do not show yield plateau and show continuous curve. For such steel, how is the yield strength obtained? (a) By drawing 0.% offset of the strain (b) By drawing 0.5% offset of the strain (c) By drawing initial tangent (d) By drawing initial secant modulus 14. Where should splices in the columns be provided (a) At the floor levels (b) At the mid height of columns (c) At the beam-column joints (d) At one-fourth height of columns 15. Why are tie plates provided in laced columns? (a) To check the buckling of columns as a whole (b) To check the buckling of the lacing flats (c) To check the buckling of the component columns (d) To check the distortion of the end cross sections 16. The slenderness ratio of lacing bars should not exceed (a) 100 (b) 10 (c) 145 (d) Which one of the following is a compression member? (a) Purlin (b) Tie (c) Girt (d) Boom Page of 14

3 18. Angle of inclination of lacing bars in a built-up column is constrained as 70 o > ɵ>40 o,where o is angle of lacing with vertical, When this limit is not maintained, the total length of bar will be large. 19. Which is the maximum permissible slenderness ratio of a major compression member which undergoes reversal of stress due to wind load? (a) 180 (b) 50 (c) 400 (d) Which one among the following is the correct ratio of effective length to actual length of a discontinuous angle strut, if ends are welded? (a) 0.65 (b) 0.85 (c) 1. (d) A compound column had been fabricated with 4 angles of ISA 50 x 50 x 6 placed at corners of a square 300mm x 300mm. The radius of gyration of the angle is 10mm. For the fabricated column, the overall slenderness ratio is 40. What is the maximum distance between lacing bar attachments at the fabricated columns? (a) 500mm (b) 400mm (c) 300mm (d) 80mm. Which one of the following forces is used for the design of battens of built-up columns? (a) Axial load (b) Twisting moment (c) Vertical shear (d) Transverse shear 3. Single lacing systems on opposite planes shall preferably be in the same direction so that one is the shadow of the other. 4. Lacing bar should be a flat section. 5. Laced compression members are to be provided with tie plates at ends. 6. The batten plates used to connect the components of a built-up column are designed to resist (a) Longitudinal shear only (b) Longitudinal shear and moment and arising from transverse shear (c) Transverse shear only (d) Vertical shear only Page 3 of 14

4 7. In ISMC 400 channels placed back to back at a spacing of 6 cm carry an axial load of 160 tonnes. The lacing system should be designed to resist a transverse shear of (a) 16 tonnes (b) 1 tonnes (c) 8 tonnes (d) 4 tonnes 8. Consider the following parameters with regards to slenderness ratio of a compression member: 1. Material. Sectional configuration 3. Length of member 4. Support end conditions On which of these parameters does the slenderness ratio of a compression member depend? (a) 1, and 3 only (b) 1, 3 and 4 only (c), 3 and 4 only (d) 1,, 3 and A column member of length l which cannot sway has a rigid foundation at its bottom. Its top is held with heavy beams. The effective length of the column is (a) 1.5L (b) 1.0L (c) 0.8L (d) 0.65L 30. A steel column pinned at both ends has a buckling load of 00kN. If the column is restrained against lateral movement at its mid-height, its buckling load will be (a) 00kN (b) 400kN (c) 38kN (d) 800kN 31. In laced columns, end tie-plates are provided to (a) Check the buckling column (b) Keep the column components in position (c) Check the distortion of column sections at ends because of unbalanced horizontal force from lacings. (d) Prevent rotation of elements. 3. A column is effectively held in position and restrained in direction at one end but is free at the other end. If the actual length is L, the effective length is (a) 0.67L (b) L (c) 1.5L (d) L 33. If the crushing stress in the material of a mild steel column is 330 N/mm. Euler s Formula for crippling load is applicable for slenderness ratio equal to/greater than (a) 40 (b) 50 (c) 60 (d) 80 Page 4 of 14

5 34. Which one of the following pairs is not correctly matched? Boundary Conditions of column Euler s Buckling load (a) Pin-Pin P cr = ( ) K L (b) Fixed-Fixed P cr = 4 ( K L) (c) Fixed-Pin P cr = ( K L) (d) Fixed-Pin P cr = 0.5 ( K L) 35. The buckling load for a column of specified material, cross-section and end conditions calculated as per Euler s formula varies inversely with the column length. 36. Euler s formula takes into account the end conditions in determining the effective length of column. 37. The slenderness ratio of a section is (a) Directly proportional to the radius of gyration (b) Directly proportional to the moment of inertia (c) Inversely proportional to the area (d) Inversely proportional to the radius of gyration 38. The square root of the ratio of moment of inertia of the cross-section to its cross-sectional area is called (a) Second moment of area (c) Slenderness ratio (b) Section modulus (d) radius of gyration Page 5 of 14

6 39. Effective length of a battened column is usually increased to account for the additional load on battens due to the lateral expansion of columns. 40. The Euler buckling load of a slender steel column depends on the yield strength of steel. 41. In the design of laced column, the maximum spacing of the lacing does not depend on the slenderness of column as a whole. 4. Which of the following in not a compression member? (a) Strut (b) Tie (c) Principal rafter (d) Boom 43. Tubular sections form the most economical compression member because tubes (a) Have high lateral buckling strength (b) Have high torsional resistance (c) Are subjected to less wind force than any other sections (d) All the above 44. For equal cross sectional area, the most efficient section for column is (a) I-Section (b) Channel section (c) Circular section (d) Hallow circular section 45. From economic considerations, a built up section column (compound column section) shall have (a) r yy = r zz (b) r yy <r zz (c) r yy >r zz (d) r yy > r zz 46. Match List-I (End conditions of column) with List-II (Euler s crippling load) and select the correct answer by using codes given below the lists: List-I List-II 1. Both ends hinged P cr = ( ) K L. Both ends fixed P cr = 3. One end fixed, other end free P cr = 4. One end fixed, other end hinged P cr = 0.5 ( K L) ( K L) 4 ( K L) Page 6 of 14

7 47. Read the following statements 1. The buckling load is less than the crushing load in long columns. The buckling load is more for long columns and relatively less for short columns 3. When an axially loaded compression member just buckles, it is said to develop an elastic instability 4. When an axially loaded compression member just buckles, it is said to develop an elastic instability The correct statements are (a) Both 1 and (c) Both and 3 (b) Both 1 and 3 (d) all 1, and Euler s load of a column depends upon: 1. Length of column. Least lateral dimension 3. Cross-sectional area of the column The correct answer is (a) Only 1 (b) only 3 (c) Both 1 and 3 (d) Both 1 and 49. Euler s formula is based on the following assumptions: (a) The column is initially straight and is axially loaded. (b) The column will fail by buckling only. (c) The length of the column is very large in comparison to the lateral dimension The correct answer is (a) Only 3 (b) Both 1 and 3 (c) Both and 3 (d) ALL 50. The design compressive stress of axially loaded compression member in IS 800: 007 is given by (a) Merchant rankine formula (b) Secant formula (c) Euler formula (d) Perry Robertson formula Page 7 of 14

8 51. The effective length of a battened column is (a) Increased by 10% (b) Increased by 0% (c) 0.8 times the unsupported length of the column 5. The effective length of a strut (double angle on opposite side of gusset plate) of actual length L, in a plane of the gusset plate will be (a) 0.7-1L (b) L (c) 0.7-1L (d) 1.0L 53. The effective length of a strut (double angle on same side of gusset plate) of actual length L, in a plane perpendicular to the gusset plate will be (a) 0.7-1L (b) L (c) 0.7-1L (d) 0.85L 54. The slenderness ratio of compression members is limited to account for (a) The effect of accidental and construction loads (b) They may be used as a walkway in braced roof truss system (c) Vibrations (d) All the above 55. Single equal angle section is a better choice than a single unequal angle section for a compression member. 56. Tubes for compression members are most suited for long lengths and small loads 57. r z and r y will be approximately same for double unequal angles with long legs back to back or spread. 58. For a laced column, the effective length should be increased by 10 percent. 59. The function of lacing bars is to equalize the stress distribution in the component members of the column. 60. The buckling strength of laced column is smaller than that of solid column Page 8 of 14

9 61. Laced columns are economical than battened columns.. 6. In a double lacing system, the thickness of the lacing flats should not be less than 1/40 of the length between inner end bolts or welds. 63. Lacings are recommended with non-mirror image. 64. Alternate lacing and batten arrangement is the most efficient system. 65. Double lacing is provided when component member fails in buckling even with an inclination of 70 0 with vertical. 66. For connecting lacing flats to columns with 18mm diameter bolt, the minimum width of flat should be (a) 36mm (b) 54mm (c) 60mm (d) 55mm 67. Which of the following is not a design criterion of a lattice column? (a) Buckling of the column as a whole (b) Buckling of the component column (c) Buckling of the individual rolled sections constituting channel (d) Buckling of lattice member 68. Thickness of lacing flats for a single lacing system should be not be less than of the length between the inner end bolts (a) 1/40 (b) 1/50 (c) 1/60 (d) 1/ For same load, unsupported length and end conditions, a laced column as compared to be battened column (a) Is stronger (b) Is weaker (c) Is equally strong (d) Cannot be compared 70. The effective depth of end battens should be more than (a) The distance between the centre of gravity of the connecting members (b) The c/c distance between inner end bolts (c) Twice the flange width of component column (d) Both (a) and (c) Page 9 of 14

10 71. The thickness of lacing flats for a double lacing system should not be less than 1/60 of the length between c/c of end connection. 7. Angle of inclination θ of the lacing bar with the longitudinal axis of the component member should be kept between 40 o Failure in Long columns is generally by (a) Crushing of material (b) Elastic buckling (c) Torsional buckling (d) Inelastic buckling 74. Lacing bars in steel built up column are designed to resist (a) Bending moment resulting from.5% column load (b) Transverse shear force due to.5% of design axial load in the column (c).5% column load (d) Both (a) and (b) 75. Batten should be designed for moment due to transverse shear of (P: Axial load on column, N: Number of batten, S: Transverse distance between centroid of bolt group, V: Lateral shear on column) (a).5%p (b) VC/NS (c) VC/N (d) VC/S 76. Consider following statements for a built up compression member as per IS 800:007, 1. Laced column is stronger than battened column for same load and unsupported length and same end condition. The effective slenderness ratio length of battened column is increased by 10% 3. The slenderness ratio of lacing bar should not exceed The effective slenderness ratio of laced built up column is increased by 5% Above following statements are TRUE, is/are (a) 1, and 3 (b) and 3 (c) and 4 (d) 1,, 3 and 4 Page 10 of 14

11 77. In designing of lacing system, a single lacing systems on opposite plans shall be preferably be in the same direction, so that one is the shadow of the other is done (a) To avoid twisting of the built up column section (b) To avoid bending of the built-up column section (c) To have better architectural appearance built up columns (d) Connecting the built up columns easily 78. The slenderness ratio of a column which is supported throughout its length by masonry wall is (a) 10 (b) 100 (c) zero (d) Infinity 79. Batten provided for a compression member shall be designed to carry transverse shear equal to (a).5% of axial force in member (c) 10% of axial force in member (b) 5% of axial force in member (d) 0% of axial force in member 80. In computing the maximum slenderness ratio, the minimum value of the radius of gyration is used (a) Correct (b) Incorrect 81. A structural member subjected to compressive force in a direction parallel to its longitudinal axis, is called (a) Column (b) Post (c) Stanchion (d) Any of the above 8. When the cross-sectional area of the column is kept constant, the load required to cause failure due to direct compression as the length of column increases (a) Increases (b) Decreases 83. The lateral system used in built-up columns, to carry the transverse shear force, is (a) Lacing (b) Batten plates (c) Perforated plates (d) Any of these 84. When the components of built-up column are connected by a lateral system, the reduction in buckling strength due to shear deflection is that of solid built-up columns (a) Equal to (b) Less than (c) More than Page 11 of 14

12 85. Match List I (Types of Construction) with List II (Effective length of lacing bars) and select the correct answer List I List II A. Single lacing (Bolted construction) L B. Double lacing (Bolted construction). L C. Welded lacing A B C (a) 1 1 (b) 1 (c) 1 (d) The thickness of batten plates should be greater than 1/50 th of the distance between the innermost connecting lines or welds. 87. Critical stress of a column is directly proportional to the square of the slenderness ratio of the column. 88. Stocky columns have a very low slenderness such that they are unaffected by the member overall buckling. 89. Ultimate strength of stocky columns is reduced by residual stresses and geometric imperfections. 90. Residual stresses due to uneven cooling of standard sections after hot-rolling, and also welding, can adversely affect the resistance of columns against buckling. True /False 91. Critical buckling load is independent of the strength of the material. 9. Buckling in steel differs from buckling in concrete. 93. Buckling in steel is in one direction whereas buckling in concrete is in directions Page 1 of 14

13 94. Elastic buckling is the one that buckles under stresses smaller than the proportional limit. 95. Long columns usually fail by elastic buckling, for which Euler buckling stress is valid. 96. Euler s equations give reliable results for stocky or less slender compression members. 97. Inelastic buckling is the one that buckles under stresses below the proportional limit. 98. The factors affecting the strength of column of a column in practice: (a) Effect of initial out of straightness (b) Effect of eccentricity of applied loading (c) Effect of residual stress (d) Effect of a strain hardening and the absence of clearly defined yield point (e) All the above 99. The strength of compression members subjected to axial compression is defined by curves corresponding to following different classes: (a) a, b and c (b) e and f (c) e, f and g (d) a, b, c and d 100. The buckling curves a, b, c and d depends on (a) The shape of the column cross-section considered, (b) The direction in which buckling can occur (y axis or z axis) (c) The fabrication process used on the compression member (hot-rolled, welded or coldformed). (d) All the above 101. The best compression member section for columns is (a) Single-angle section (c) double-angle section (b) Channel-section (d) I-section 10. The best double-angle compression member section is (a) Unequal angles with short legs connected (b) Unequal angles with long legs connected (c) Unequal angles on same side of the gusset plate (d) Equal angles on opposite side of gusset plate Page 13 of 14

14 103. Match List I (Types of members) with List II (Slenderness ratio) and select the correct answer using the codes given below the lists: List I List II A. For compression members carrying Dead and live loads B. For members carrying compressive. 180 due to wind or seismic force only C. Compression flange of a beam restrained against lateral torsional buckling A B C (a) 1 3 (b) 1 3 (c) 3 1 (d) 1 3 Page 14 of 14