Tuesday, July 10, 2018

Solved Example of Pinned Truss - the average normal and shear stresses in members and pins respectively and Pin Diamater

Hi,
A simple truss has pin-connected members. The members carry only axial forces, but the pins have to bear the shear stresses. Given example shows the calculation for the minimum required diameter of pin connected in double shear.

Problem: Two structural members AB and BC (shown below) are connected by a pin at B that is subjected to two 5-kip horizontal forces. The pins used at A and C are identical to the pin at B. The allowable shear stress for pins is 15 ksi, and the allowable bearing stress for members AB and BC is 20 ksi. Determine:
(a) the maximum average normal stress in members AB and BC.
(b) the minimum required diameters of the pins.


Solution:


Area of traverse by Average End Area Method - Solved Example

Hi,

For the trapezoidal sections, when the end heights are given, the area can be found by averaging the end heights and multiplying it with the distance between those heights.

Given examples show the closed traverses with the straight baselines.


Solution:

Friday, April 20, 2018

How to Balance a Closed Traverse - Use of Compass(Bowditch) Rule - Solved Example

Hi,

Problem:
Following is the Field Data for a 4 sided, closed traverse, and you have to find the azimuth, bearings and corrected distances using Compass Rule or Bowditch Method.



Solution: 
Download the image, solution is written for the angular closure, correction, azimuth, bearings, latitude and departure and corrected distance calculations. 

Thursday, April 19, 2018

Derivation of Mass moment of Inertia for a Solid Cone

Hi,

Problem:
Derive the Mass Moment of Inertia of a solid cone with given mass density and angle half at vertex equal to 35 degrees. If the length of the cone is 5 m and mass density is 2.5 kg/m3, what is the mass moment of inertia. 

Solution:

Wednesday, April 18, 2018

Complete Derivation of Mass Moment of Inertia of Hemisphere(Half Sphere) about the symmetric axis of Rotation.

Hi,

Problem: 
The top half of the sphere is created by rotating the circle of x2+y2=r2 around the y-axis. If the rigid body has mass m and density (rho), find the mass moment of inertia about y-axis in terms of m and rho. 





Solution:

Monday, April 16, 2018

How to Plot graph with Multiple Data Sets in Microsoft Excel (scatter function)

Hi,

If you have more than one data sets to be plotted on the graph, you can easily do that in excel under the 'insert'  scatter option. Follow the given eight steps with images. 


Step.1 Make three data sets separately, and choose 'scatter' graph under 'insert' menu.



Step.2 Right click on the scatter graph, and select 'select data'



Step.3 Click on add and a small box will pop up. Give any series name, say 'Data Set 1', select all cells containing x -axis and y-axis values for the corresponding given boxes.Once you click 'ok' those blue data dots will appear on the scatter. 


Step. 4 Now again click 'add' in the select data option, and then give another series name, say 'data set 2' and choose the corresponding data from data set 2 on the cells. Once done, those maroon colored dots will appear corresponding to 2nd data set.




Step. 5 Repeat step.4 for data set 3, and those light green dots will appear.
your 'select' data box will have now three series of data, and you can edit them or remove them, or you can even add another data set, by clicking on 'add'



Step.7 You can add trendlines to make it more appealing.
click on the series for which you want to add trendlines, once dots get selected, give a righ click, and this add trendline option will appear.


select among various options, how you want it to appear, linear, polynomial, etc. are various options, here I am selecting 'moving average.'



If you do same for all three series, this is how the final graph look like.



Thank you for vising!
Take care!

Friday, April 13, 2018

Use Method of Section on Gambrel Truss and Find section Forces - Solved Example


Hi,

Problem:
This is a Gambrel Truss with 5 known load forces on it as shown below. Let's say the reaction forces are already found, at A(0, 959.6 N) and at H(0, 450 N). Each applied load is 300 N.

Use the method of sections to determine all the unknown external forces acting on section ABG. Using your results, list whether members BD, BE, and EG are in compression or tension?



Solution:



Thank you for your kind visit.

Solved Example of Pinned Truss - the average normal and shear stresses in members and pins respectively and Pin Diamater

Hi, A simple truss has pin-connected members. The members carry only axial forces, but the pins have to bear the shear stresses. Given exa...