(a)
The girder cross section and the spacing of intermediate stiffeners that is required.
Answer to Problem 10.7.7P
Web dimensions
Flange
Explanation of Solution
Given information:
Span length
Uniform dead load
Uniform live load
Dead load
Live load
Depth
Calculation:
Determine girder cross section and girder spacing of intermediate stiffeners.
Calculate design strength.
Try
Determine the trial web size.
Consider the condition for the web to slender.
Estimate the web thickness from the following limitations:
Estimate the web thickness from the following limitations:
From the estimated limit of
Determine area of web.
Determine area of flange.
Determine the breadth of flange.
Conclusion:
Therefore, girder size of
(b)
The size of intermediate and bearing stiffeners.
Answer to Problem 10.7.7P
Web size
Bearing stiffeners
Explanation of Solution
Given information:
Span length
Uniform dead load
Uniform live load
Dead load
Live load
Depth
Calculation:
Calculate the elastic section modulus by using the formula.
Moment of inertia is given by,
Calculate the maximum distance whichis given by,
Elastic section modulus about the axis
From
Radius of gyration is given by,
Calculating the moment of inertia.
Determine area of cross-section.
Radius of gyration is given by,
Unbraced length
Determine the
Determine the
Since
Calculate compression flange strength.
Calculate bending strength reduction factor.
Determine compression flange strength.
For proper flexural strength,
Conclusion:
Therefore, stiffeners are not needed in the middle and use girder size of
(c)
Design of all welds.
Answer to Problem 10.7.7P
Web dimensions
Flanges
Explanation of Solution
Given information:
Span length
Uniform dead load
Uniform live load
Dead load
Live load
Depth
Calculation:
Calculate the elastic section modulus by using the formula,
Moment of inertia is given by,
Calculate the maximum distance which is given by,
Elastic section modulus about the axis
From
Radius of gyration is given by,
Calculating the moment of inertia,
Determine area of cross-section.
Radius of gyration is given by,
Unbraced length
Determine the
Determine the
Since,
To calculate the plate girder strength reduction factor values,
Calculate compression flange strength.
Calculate proper flexural strength.
Calculate nominal shear strength.
Check for design strength.
Compute the value of
Assuming the equation
Hence, equation
Determine the value of
Calculate the value of required shear strength
Compute the value of required shear
Using the curves in the table
Values obtained are shown below,
By interpolation determine the value of
Use the value
Compute the value required to shear strength from the left end,
Compute the value of required shear
Values obtained are shown blow,
By interpolation we get the value of
Use the value
Calculate to shear strength from the left end.
Calculate shear
Values obtained are shown blow,
By interpolation calculate the value of
Use the value
We can use next stiffener will be used at
Calculate distance remaining concentrated load.
Calculate shear strength
Calculate the required shear
Conclusion:
Therefore, girder size of
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