Help Required - Beam Curve Measurement

**Dafty** · Nov1-09, 07:24 AM

Hi wonder if there is anyone out there who can help me !!
Whats the easiest formula for working out the measurement of curveture in a simply supported structural horrizontal monorail beam.
Any help most appreciated. - thanks

**Scudley** · Nov3-09, 01:48 PM

Do you want to know how to measure the actual curvature of an existing structure or predict the curve of a planned structure?

If you want to predict: If the beam is straight and and a steel section, it is not that complicated, it gets more complicated if the monorail track is concrete. It get very complicated if the beam curves. There are mathematics that allow you to calculate the curve of the unloaded beam as well as under load.

**jamesd2008** · Nov3-09, 06:56 PM

Don't know if this is any help but here is the engineers bending theory equation

M/I=sigma/y=E/R

were

M=moment
I=second moment of area
Sigma=stress
y=neutral axis
E=youngs modulus
R=The radius of curviture of the beam

**Dafty** · Nov4-09, 05:05 AM

Originally Posted by Scudley

Do you want to know how to measure the actual curvature of an existing structure or predict the curve of a planned structure?

If you want to predict: If the beam is straight and and a steel section, it is not that complicated, it gets more complicated if the monorail track is concrete. It get very complicated if the beam curves. There are mathematics that allow you to calculate the curve of the unloaded beam as well as under load.

Thanks for yor reply Scudley - i need to take curveture measurements from an existing horizontal simply supported monorail beam - whats the easiest way of measuring and working out radius curve - eg 60 - 90 degrees.

Thanks in advance Scudley - Iam the dafty here

**Dafty** · Nov4-09, 05:07 AM

Originally Posted by jamesd2008

Don't know if this is any help but here is the engineers bending theory equation

M/I=sigma/y=E/R

were

M=moment
I=second moment of area
Sigma=stress
y=neutral axis
E=youngs modulus
R=The radius of curviture of the beam

Thanks for your support reply James - i need to work out curviture of an existing beam

**FredGarvin** · Nov4-09, 07:57 AM

What size is this beam? Are we talking something that is very large or just a lab experiment?

**Dafty** · Nov4-09, 09:33 AM

Originally Posted by FredGarvin

What size is this beam? Are we talking something that is very large or just a lab experiment?

Fred this beam is currently in situ - runs approx 60ft long simply supported via vertical welded supports and constructed from standard American stardard I beam 4 " Wide x 8 " High has one curve of which iam trying to determine easiest way to measure and work out radius curve.

Thanks

**FredGarvin** · Nov4-09, 12:28 PM

With something that long, have you looked into the possibility of a transit used by surveyors? They can be quite accurate.

**Dafty** · Nov10-09, 08:28 AM

Originally Posted by FredGarvin

With something that long, have you looked into the possibility of a transit used by surveyors? They can be quite accurate.

Hey iam stuck here !! have only got plum lines and a measuring tape, does anyone know the answer to my query - beam is approx 60ft long and has one curve - looks like 90 degree although again i,am looking for the easiest formula to determine.

Thanks

**CarlAK** · Nov11-09, 03:19 AM

Measure the length along the curve (beam), the chord (straight line distance from beginning to end of the curve, and the maximum distance between the straight line and the curve. Actually you only need any 2 of these measurements. Now draw a sketch of an arc, center of arc, radius, chord, angle of arc, and use some trigonometry.