General Design Principles MCQ Quiz in मल्याळम - Objective Question with Answer for General Design Principles - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Explanation:

As per IS code 800 : 2007, clause 16.4.1

The influence of temperature on the yield stress of steel shall be taken as follows for the structure of mild steels and high strength low alloy steels

\({f_{y}(T)\over f_{y}(20)}={905-T\over 905}\leq1.0\)

f_y(T) = Yield stress of steel at T°C,

fy(20) = Yield stress of steel at 20°C

T = Temperature of steel in °C.

For temperature less than 215°C no reduction in the yield stress needs to be considered.

Concepts:

The principle mechanical properties of the structural steel important in design, as detailed by the code IS 800:2007 in cl. 2.2.4.2, are:

1. Yield stress
2. Tensile or ultimate stress 
3. The maximum percent elongation on a standard gauge length and
4. Notch toughness

Note:

The various Physical properties of structural steel irrespective of its grade, as detailed by cl.2.2.4.1 of IS 800:2007 are:

1. Unit weight of steel = 7850 kg/m³
2. Modulus of elasticity, E = 2.0 x10⁵ N/mm² 
3. Poisson ratio, μ = 0.3
4. Modulus of rigidity, G = 0.769 x 10⁵ N/mm²
5. Coefficient of thermal expansion α = 12 x 10^-6/⁰C.

Concept:

Prevention of Local Buckling:

The local buckling can be prevented by adopting a higher thickness value for the plate element IS800:2007 puts a limit on width to thickness ratio of component steel plates of the section as given in Table 1.1.

Where, 

ϵ = \(\sqrt \frac{250}{f_y}\)

f_y = Yield strength of Steel

Concept:

Permissible stresses in steel,

Where, f_y = Yield stress

Calculation:

Given,

Yield stress (f_y) = 420 MPa

Permissible stress in axial tension is given by,

Permissible stress = 0.6 f_y = 0.6 × 420 = 252 MPa

Specification for the pitch of bolts or rivets

1. Minimum pitch and minimum gauge length

\( = \left\{ {2.5 \times nominal\;diameter\;of\;the\;bolt} \right.\)

2. Minimum end and edge distance

\(= \left\{ {\begin{array}{*{20}{c}} {1.5 \times diameter\;of\;the\;bolt\;hole,\;for\;machine\;cut\;element}\\ {1.7 \times diameter\;of\;the\;bolt\;hole,\;for\;hand\;cut\;element} \end{array}} \right.\)

3. Maximum end and edge distance

\(= \left\{ {\;12 \times t \times \epsilon,\;\begin{array}{*{20}{c}} {\;where\;\epsilon = \sqrt {\frac{{250}}{{{f_y}}}} }\\ {{f_y} = yield\;stress}\\ {t = tickness\;of\;thinner\;plate\;} \end{array}} \right.\)

4. Maximum pitch of bolts or rivets or welds in the compression zone 

\(= \left\{ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {12 \times t\;}\\ {or}\\ {200\;mm} \end{array},\;whichever\;is\;less}\\ {\;t = thickness\;of\;the\;thinner\;plate} \end{array}} \right.\;\)

5. Maximum pitch of bolts or rivets or welds in the tension zone

\(= \left\{ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {16 \times t\;}\\ {or}\\ {200\;mm} \end{array},\;whichever\;is\;less}\\ {\;t = thickness\;of\;the\;thinner\;plate} \end{array}} \right.\)

6. If bolts are Staggered, the above values can be increased by 50%, i.e. 

\(Maximum\;pitch\;in\;compression = \left\{ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {18 \times t\;}\\ {or}\\ {300\;mm} \end{array},\;whichever\;is\;less}\\ {\;t = thickness\;of\;the\;thinner\;plate} \end{array}} \right.\)

\(Maximum\;pitch\;in\;tension\;zone = \left\{ {\begin{array}{*{20}{c}} {\begin{array}{*{20}{c}} {24 \times t\;}\\ {or}\\ {300\;mm} \end{array},\;whichever\;is\;less}\\ {\;t = thickness\;of\;the\;thinner\;plate} \end{array}} \right.\)

Explanation:

As per IS 800 (2007): General Construction In Steel - Code of Practice:

Rigid construction

• In rigid construction, the connections between members (beam and column) at their junction shall be assumed to have sufficient rigidity to hold the original angles between the members connected at a joint unchanged under loading.

Semi-rigid construction

• In semi-rigid construction, the connections between members (beam and column) at their junction may not have sufficient rigidity to hold the original angles between the members at a joint unchanged, but shall be assumed to have the capacity to furnish a dependable and known degree of flexural restraint. The relationship between the degree of flexural restraint and the level of the load effects shall be established by any rational method or based on test results.

Simple construction

• In simple construction, the connections between members (beam and column) at their junction will not resist any appreciable moment and shall be assumed to be hinged. 

As per IS: 800 - 2007, Clause 10.5.2.3, Table 21

Explanation:

Explanation:

Notional load:

• A notional load is a lateral load that is derived from an existing vertical load case.
• This load type has been introduced to accommodate a requirement in design codes.
• It accounts for the initial imperfections of the structure geometry. The AISC 360-05 specification for example defines notional loads as lateral loads that are applied at each framing level and are specified in terms of gravity loads.

Rotational load:

Rotational load defines loads resulting from the rotation of the model. You can specify either angular velocity or rotary acceleration. Abaqus defines the load by using the square of the angular velocity or by using the acceleration directly. In either case, the load definition must include an axis of rotation, which is defined as follows:

• If you are working in three-dimensional space, you define the location and direction of the axis by entering the global coordinates of two points.
• If you are working in two-dimensional space, you specify the location of the axis by entering the coordinates of a point in the plane. The direction of the axis is always out of the plane.
• If you are working in axisymmetric space, the axis is always in the location and direction of the positive global Z-axis.