Q21GATE 2010MCQ

Two plates, subjected to direct ension, each of 10 mm thickness and having widths of 100 mm and 175mm, respectively are to be fillet welded with an overlap of 200 mm. Given that the permissible weld stress is 110MPa and the permissible stress in steel is 150MPa, the length of the weld required using the maximum permissible weld size as per IS : 800-1984 is

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📖 Explanation

The maximum size of a fillet weld is obtained by subtracting 1.5 mm from the thickness of the thinner member to be jointed. $\therefore \;\; S=10-1.5=8.5 mm$ Strength of the thinner plate $=100\times 10\times 150\times 10^{-3}=150kN$ Strength of the weld

\begin{aligned} &=L\times S\times 0.7\times \sigma _{WS} \\ \Rightarrow \;\; 150\times 10^{3}&=L\times 8.5\times 0.7\times 110 \\ \Rightarrow \;\; L&=229.18 mm\simeq 229.2 mm\end{aligned}

Q23GATE 2009MCQ

A 12 mm thick plate is connected to two 8 mm thick plates, on either side through a 16 mm diameter power driven field rivet as shown in the figure below. Assuming permissible shear stress as 90 MPa and permissible bearing stress as 270 MPa in the rivet, the rivet value of the joint is

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📖 Explanation

Rivet value is the lesser of shearing strength or bearing strength of rivet. Shearing strength of rivet $=2\times \frac{\pi }{4}\times \left ( 16+1.5 \right )^{2}\times 90=43.29kN$ Bearing strength of rivet $=\left ( 16+1.5 \right )\times 12\times 270=56.7kN$ $\therefore$ Rivet value of the joint = 43.29 kN

Q24GATE 2008MCQ

Rivets and bolts subjected to both shear stress ( $\tau _{vf,cal}$ ) and axial tensile stress ( $\sigma_{tf,cal}$ ) shall be so proportioned that the stresses do not exceed the respective allowable stresses $\tau _{vf}$ and $\sigma_{tf}$ and the value of $(\frac{\tau _{vf,cal}}{\tau _{vf}}+\frac{\sigma _{tf,cal}}{\sigma _{tf}})$ does not exceed

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📖 Explanation

As per clause 8.9.4.5 of IS 800:1984 rivets and bolts subjected to both shear and axial tension shall be so proportioned that the shear and axial stresses calculated do not exceed the respective allowable stresses $\tau _{vf}$ and $\sigma _{tf}$ and the expression $\left ( \frac{\tau _{vf,cal}}{\tau _{vf}}+\frac{\sigma _{tf,cal}}{\sigma _{tf}} \right )$ does not exceed 1.4.

Q25GATE 2007MCQ

A bracket connection is made with four bolts of 10 mm diameter and supports a load of 10 kN at an eccentricity of 100 mm. The maximum force to be resisted by any bolt will be

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📖 Explanation

Bolt will be subjected to direct shear and shear force due to twisting moment. $F_{1} =$ Force on bolt due to direct shear $F_{2}=$ Force on bolt due to twisting moment

\begin{aligned} F_{1}&=\frac{P}{4}=\frac{10}{4}=2.5\, kN \\ F_{2}&= \text{stress due to moment } \\ F_{2}&=\frac{\left ( Pe \right )\times r_{1}}{\sum r^{2}_{i}} \\ r_{1} &= r_{2} =r_{4} \\ &= \sqrt{30^{2}+40^{2}}=50 mm \\ F_{2}&=\frac{10\times 100\times 50}{2500\times 4}=5 kN \\ \tan \theta &=\frac{30}{40} \\ \theta &=37^{\circ} \\ &\text{Resultant force} \\ &=\sqrt{F_{1}^{2}+F^{2}_{2}+2F_{1}F_{2}\cos \theta } \\ &=\sqrt{\left ( 2.5 \right )^{2}+\left ( 5 \right )^{2}+2\times 2.5\times 5\times \cos 37^{\circ}} \\ &=7.16\, kN \end{aligned}

Q26GATE 2005MCQ

Which one of the following is NOT correct for steel sections as per IS:800-1984 ?

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Q27GATE 2005MCQ

A fillet-welded joint of 6mm size is shown in the figure. The welded surfaces meet at 60-90 degree and permissible stress in the filled weld is 108 MPa. The safe load that can be transmitted by the joint is

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📖 Explanation

Total weld length $=\left ( 100\times 2 \right )+50=250 mm$ Strength of weld per mm length $=0.70\times 6\times 108=453.6N$ Maximum load taken by joint $=\frac{453.6\times 250}{1000}=113.4kN$

Q28GATE 2004MCQ

Rivet value is defined as

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Q29GATE 2004MCQ

A moment M of magnitude 50 kN-m is transmitted to a column flange through a bracket by using four 20 mm diameter rivets as shown in the figure. The shear force induced in the rivet A is

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📖 Explanation

The centroid of rivets will be on the symmetric lines and each rivet will be at, $r= \sqrt{\left ( 50 \right )^{2}+\left ( 50 \right )^{2}}=50\sqrt{2} mm$ Shear force in rivet A is given by, $F_{s}=\frac{Mr}{\sum r^{2}} =\frac{50\times 10^{3}\times 50\sqrt{2}}{4\times \left ( 50\sqrt{2} \right )^{2}}=176.8\, kN$

Q30GATE 2002MCQ

ISA 100x100x10 mm (Cross sectional area = 1908 m $m^{2}$ ) is welded along A and B (as shown in figure), such that the lengths of the weld along, A and B are l1 and l2, respectively. Which of the following is a possibly acceptable combination of l1 and l2

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📖 Explanation

CG of angle from A will be,

\begin{aligned} \bar{h}&=\frac{\left ( 100\times 10 \right )50+90\times 10\times \left ( 90+5 \right )}{100\times 10+90\times 100} \\ &= 71.31 \text{ mm joint A} \end{aligned}

Let $P_{1}$ and $P_{2}$ force is resisted by weld at A and B respectively then by taking moment about CG

\begin{aligned} P_{1}\times 71.33&=P_{2}\times \left ( 100-71.33 \right ) \\ P_{1}&=0.4P_{2} \end{aligned}

As $P_{2} \gt P_{1}$ (about 2.5 times) weld required on 'B' side will be more than A by 2.5 times. If $I_{1}=$ length of weld at $A =60 mm$ $I_{2} =$ length of weld at $B=60\times 2.5 =150 mm$

Q31GATE 2001MCQ

Identify the most efficient but joint (with double cover plates) for a plate in tension from the patterns (plan views) shown below, each comprising 6 identical bolts with the same pitch and gauge.

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