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Re: Beam Analysis
[Subject Prev][Subject Next][Thread Prev][Thread Next]- To: "SEAINT Listservice" <seaint(--nospam--at)seaint.org>
- Subject: Re: Beam Analysis
- From: "Structuralist" <dennis.wish(--nospam--at)gte.net>
- Date: Thu, 23 Nov 2000 00:46:41 -0800
Tom, Rather than trying to figure out the method of Enercalc - which I doubt that Mike Brooks would care to share, I would make the following guess as to how I would set it up: 1. Using the standard load formulas for multiple concentrated load, trapezoidal and uniform loads, develop the formulas where the loads ARE NOT continuous along the full length of the beam. 2. You will need conditional statements to handle the conditions based on the location of the start and finish point of the load so that the conditions that trigger various conditions in the beam calculations based on the load location is tested. This does not have to be an iterative process and can simply be done by establishing a simple flow chart and using the path as the conditional. 3. Treat each load condition as a separate beam. The shear, moment and deflection are additive at each point along the beam. 4. Break the beam into say 100 points along it's length so as to calculate the shear, moment and deflection at each of the points and apply conditionals to pull out the maximum values. This table is easily used to graph the results as well. The trick is insuring that you have sufficient size spreadsheet to accommodate a decent number of load conditions. I have been teaching this process to my students at College of the Desert. Their problem was that they could resolve a problem with multiple concentrated loads and another with multiple uniform loads, but were lost when the conditions were combined. I ran through the problems at various points along the beam and showed them how to developed the formulas using a,b, and c (etc) for the individual distance between loads and start and finish points of other loads. In uniform loads, I used a prime condition (ie. a') to represent the changeable dimension. This allowed them to understand that while within a uniform load, you treat the moment arm slightly different than if you were outside the uniform load. This seemed to work and they are having less problems. The point is that it was obvious that the build up of the formulas allowed the students and me to see the logic and relationship as we moved further to the right of the beam. The resulting formulas would simplify the programming steps and logic. It does get cumbersome, but when you consider the additive nature at each point on the beam, you are not trying to solve for the exact moment or deflection, but you are increasing the accuracy as you increase the number of points on the beam. If this does not help, go to the spreadsheet forum on the Structuralist professional page (http://www.structuralist.net) and take the link on the left side of the page to the spreadsheet forum. Graphics can be use as can links to sample spreadsheets where we can work through the problem. Hope this helps you. Regards, Dennis S. Wish, PE The Structuralist Administrator for: http://www.structuralist.net AEC-Residential Listservice admin(--nospam--at)structuralist.net (208) 361-5447 E-Fax The Structuralist is a Public, Professional and Educational website devoted to issues on Housing. You are invited to participate or simply visit our discussion forums at" http://www.structuralist.net/cgi-local/UltraBoard/UltraBoard.cgi NOTE: YOU MUST REGISTER (FREE) WITH THE SITE TO POST REPLIES OR MESSAGES. Our Residential Listservice is open to all professionals in the building industry and the discussions include code compliance issues as well as quality of construction, prescriptive vs. full compliance, present and future code development and more. The AEC-Residential List is by subscription (always free). To subscribe send an e-mail to one of the following addresses: For Full Listservice: aec-residential-request(--nospam--at)polhemus.cc For Digest Format: aec-residential-digest-request(--nospam--at)polhemus.cc To subscribe OR Unsubscribe - enter one of the following words in the body of the message and send. Do not place information in the subject line as it will be ignored. subscribe unsubscribe _____________________________ AEC-Residential - Discussion List for the Residential Building Professional To Subscribe/Unsubscribe, Send Mail to mailto:aec-residential-request(--nospam--at)polhemus.cc Leave the Subject Line Blank, put "subscribe" or "unsubscribe" in the Body of the Message (without "quotes" of course!) From: "Tom VanDorpe" <tvandorpe(--nospam--at)vcaengineers.net> To: <seaint(--nospam--at)seaint.org>, <bpolhem(--nospam--at)swbell.net> Subject: Re: Beam Analysis Bill, thanks for your responce, but I need to develop a beam program to work with our other in-house software. So my question is, how do beam programs like Woodworks and Enercalc calculate stress and deflection for general loads? Is it a numerical integration? Tom VanDorpe VanDorpe Chou Associates, Inc. (714) 978-9780
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