Understanding Moment Distribution in Beam Analysis

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SUMMARY

The discussion focuses on the moment distribution method in beam analysis, specifically addressing the calculations for moments at nodes. Participants clarify the redistribution of moments based on determined ratios, with specific values of 240 and 250 being referenced. The calculations involve negating values and redistributing them proportionally between columns at the same node. The final values discussed are 4 and 6, derived from the redistribution process involving the moments at adjacent nodes.

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  • Understanding of moment distribution method in structural analysis
  • Familiarity with beam analysis concepts and terminology
  • Basic knowledge of structural equilibrium and load distribution
  • Proficiency in using structural analysis software (e.g., SAP2000 or ETABS)
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  • Study the principles of moment distribution in structural engineering
  • Learn how to apply the moment distribution method using SAP2000
  • Research the effects of load distribution on beam moments
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Structural engineers, civil engineering students, and professionals involved in beam analysis and moment distribution calculations will benefit from this discussion.

fonseh
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Homework Statement


For the circled part , i don't understand why it's 4 and 6 . I know that it's about distribute the moment according to the ratio that we have determined earlier .

Homework Equations

The Attempt at a Solution


For 4 , shouldn't it be 240*0.4 = 96 ? For 6 , shouldn't it be 250*0.6 = 120 ?
 

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fonseh said:
shouldn't it be 240*0.4 = 96
Seems to me that the process is
  1. Take the number in line 4, negate it, and in line 5 redistribute that between that column and the other column for the same node in proportion to the DFs for those two columns. Some line 5 entries will be the sum of two such redistributions.
  2. Transfer half the number in line 5 to line 6 in the neighbouring column of the adjacent node.
So at the point you query we have -0.6 x 240 - 0.6x(-250)=6, etc.
 
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