Talk:Moment distribution method

Moment diagrams

Nice article - my thanks to whoever wrote it. One comment - there is no standard engineering convention for moment diagrams - I propose making a clarification on this point. It is usual at Cal Poly and in the UK to show positive bending moment on the tension side of the diagram. --Muchado (talk) 03:53, 13 February 2008 (UTC)

Date of use

As a retired structural designer I can tell you for sure that this method was in common use well after 1960. wgoetsch (talk) 14:26, 11 March 2008 (UTC)

Error in the diagrams

Hello.

I found an error in the example shown in Wikipedia for the Moment Distribution Method. The first load (P) is located at a distance a = 3 meters measured from the left support. The Fixed End moments are calculated correctly, but when it comes to the determination of the shear and moment diagram it was assumed wrongly that the load is now located at the middle of the first span.

Respectfully.

David Guerrero. Civil/Structural Supervising Engineer. Worley Parsons. 713 407 7271. —Preceding unsigned comment added by Warrywall (talk • contribs) 06:34, 13 August 2008

I've corrected them. Thanks. --Sjhan81 (talk) 05:43, 28 September 2008 (UTC)

distribution factors

Hello,

Where you equate the DFs of A → B and D → C, there is an error. The distribution factor from an exterior fixed support to an interior support is equal to 0. The fixed support to the right has an assumed infinite rotational stiffness. Therefore the DF from D to C = (K sub DC)/(K sub DC+∞). Hence, DF sub DC approaches (0)zero as the stiffness of the support approaches (∞)infinity. Sorry, I'm not so great with the syntax in wiki.

Robert J. Miller III, E.I.T. Staff Engineer Engineering & Technical Consultants Columbia, MD

Structural Analysis, 6th ed. R.C. Hibbelar Chapter 12, pp 469-481 —Preceding unsigned comment added by Robvh1984 (talk • contribs) 16:34, 18 June 2009 (UTC)

Error in Diagrams

I guess the diagrams for first span are not correct. Shear force should be 5.84 (not 3.84) and -4.16 (not -6.16). Maximum bending moment should be 17.5 (not 19.2). — Preceding unsigned comment added by Saeed3285 (talk • contribs) 08:33, 19 October 2011 (UTC)

I agree. I am a civil engineer employed with the Babcock and Wilcox Company. The first two beam reactions should be 5.843 kN and 9.295 kN, respectively. The values reported in the example are about 2 kN too high. I also agree that the bending moment at the 3 meter location of first load, "P" should be 17.529 kN-m. Tom Holderread, P.E. — Preceding unsigned comment added by TomTiggerBeam (talk • contribs) 03:06, 29 September 2014 (UTC)

Hardy Cross Calculation Tool

Hardy Cross moment distribution method is being taught in Theory of Structures 2 as an actual tool to integrate wind shears and effects of earthquakes on frames of a high rise building. On small frames, the calculations are manageable with the use of a calculator. On medium sized frames, an electronic spreadsheet such as Excel can be used. But with frames involving thousands of nodes and points, encoding formulas on spreadsheet will be too tedious. Luckily, someone has uploaded an Android app that handles thousands of elements! This would allow engineers and architects to realistically evaluate moments in large or tall structures.

The said Android app is generic and minimalist in design. Data can be encoded in delimited text format. Sadly, as of publication time, the app does not offer a satisfactory convenience in data encoding; the engineer has to calculate and supply values for distribution factors (DF's) and initial fixed-end moments (FEM's) manually. The developer seemed to care only for the final (balanced) moments. Nonetheless, the app is a real number-cruncher with very high degree of accuracy and speed!

Get this app from Google play store for FREE.