Questions tagged [beam]

Questions about the theory and applications of structural elements designed to resist bending.

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2 answers
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Post and steel rope framework for grape vine

I am planning to build a framework to support a grape vine above a patio. Ideally I would like to use steel rope to provide this framework, rather than a full timber frame. Diagram attached. There is ...
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17 views

Why don't we calculate buckling in composite beams?

I have a frame, it consists of steel beams and my flooring is a composite deck. It consists of composite beams that are hinged to my steel frame beams. Composite beams do not transfer moments. Now, ...
1 vote
3 answers
136 views

How many support beams/rods needed for a firewood storage cabinet

I am building a firewood storage cabinet which should support around 100-150 kg of firewood. The cabinet is made out of wooden boards (...
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1 answer
29 views

Calculate the deflection of a fixed supported beam

I am having a lot of trouble with the below question. Im not really sure how to calculate the deflection of the x coordinate, how do i go about completing this question? Any help would be appreciated ...
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FInding deflection on a uniform beam with supports ~ Incorrect answer

Hello I am asked to find deflection of beam in millimetres at different points. The uniform beam is 3.55 meters long with a flexural rigidity of 32269Nm^2 It is under a uniform load of 92N/m and is ...
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9 views

Finding deflection on a uniform beam with fixed supports ~ Incorrect answer :(

This question has asked us to find the deflection of a beam (in millimeters) if the beam is under a load of: f(x) = 9.46(x+0.82)(9.2288-x) N/M The beam is supported with fixed supports at both ends ...
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1 answer
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Mechanics of Materials Method for Curved Beam with Different Centers

The common curved beam theory covered is the Winkler method (e.g. in Johnston and Beer, or Boresi and Schmidt). As can be seen by reading any derivation, this method applies to beams with a common ...
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1 answer
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Rigid frame deflection and material selection

I'm building a frame that will receive a point load mid span (likely it won't be but want to design for worse case). The frame is 1.5 x 0.095 square tubing, and it will be skinned with 14ga on one ...
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How can I mount this plate on a Steel Beam?

As mentioned in the question, I am looking for a method to attach this mounting bracket to the flange of a steel beam that permits effortless removal and remounting without permanent fixation.
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How to suppress longitudinal stress waves in a beam in FEA

When simulating a bending beam in FEA mimicking the textbook model and approach, unwanted stress waves appear. How to suppress longitudinal stress waves in a beam in FEA? To add friction/damping?
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1 answer
132 views

Modeling the Internal Forces Exerted on a Catapult Arm while Throwing

I am currently creating a MATLAB script to determine the internal forces present in a uniform beam as it is accelerated by a torsional spring. I was able to derive the equation for the axial force ...
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1 answer
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Cantilever beam

I want to design a cantilever addition. Over the driveway so I can't add supports. I want to use the calculator here https://calcresource.com/moment-of-inertia-rect.html But I'm having trouble ...
1 vote
2 answers
2k views

Multiple varying cross section beam with uniform loads

I have the following cantilever beam problem where I need to find the deflection of the tip at P. I tried to compute the deflection of the beam using Castignliano' s theorem as described in this ...
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3 answers
2k views

What's the best shape (solid of revolution) for a cantilever beam to carry a point load at the free end?

How should you change the diameter/radius (while keeping constant overall volume) of the cross-section along the length of a round cantilever beam so that you minimise deflection with concentrated ...
1 vote
1 answer
90 views

Beam load - bending design value of southern GC yellow pine for treehouse beam span

I'm looking to build a treehouse and wanting to ensure the support beams can carry a sufficient load over an 11-ft span. Based on page 78 (aka 83) of https://awc.org/wp-content/uploads/2021/12/AWC-...
1 vote
1 answer
157 views

Simple cantilever beam deflection - what is the simplest way to add a damper?

I am looking at a simple cantilever beam deflection: I understand the general expression for deflection/force would be: $$y_s = \frac{Fx_s^3}{3EI}$$ $$F_p = \frac{3y_sEI}{x_s^3}$$ If you were going ...
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1 answer
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Analysis of beams and supports

In beams when we are converting uniform disturbed load to point load, the point load is assumed to acting at the centre of length why is it so? And converting uniform varying load we assume it to act ...
1 vote
1 answer
221 views

Comparison of Shear Stress obtained from thin-walled beam theory and Timoshenko beam theory

I am studying the book "Structural Analysis with Applications to Aerospace Structures" by Craig. In Chapter 8 titled "Thin-Walled Beams", the authors derived the governing ...
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1 answer
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Which beam deflects and twists more, open section or closed section?

Two beams, one open section (like an I-beam with flanges and web) and the other closed section (like a hollow square section) are cantilevered and have the same overall cross sectional moment of ...
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1 answer
36 views

Derivation of the fundamental principle in the mechanics of beams

Can someone provide the derivation for the following equation: $$\int_l Q_Z(x) dx = M_y (x) \tag1$$ or equivalently : $$\frac{dM_y}{dx}=Q_Z\tag2.$$ I am interested in the $1D$ isotropic material ...
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31 views

Is there explicit expersion for the natural frequency of a cantilever timoshenko beam?

I am trying to find a closed form solution for the natural frequency of cantilever Timoshenko beam. In mechanical vibration (Rao, 5th edition) he outlined the details to include the Effects of Rotary ...
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1 answer
108 views

Determining the critical load of a fixed beam with non-uniform cross-section?

I am a computer scientist, not a mechanical engineer, so it is absolutely possible that I am missing some basic understanding here. I have a beam that is fixed in both ends and my goal is to ...
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2 answers
606 views

How is the limit state EQU used in Eurocode?

Quote from here: Limit state EQU, dealing with static equilibrium, is defined as: Loss of static equilibrium of the structure... considered as a rigid body, where minor variations in the [actions or ...
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2 answers
495 views

Stress and Displacement of Cantilever Plate with a Uniform Load

Does any one happen to know of any resources that describe the stress and displacement of a uniformly distributed load in the direction perpendicular to the length direction of a plate analytically? I ...
2 votes
2 answers
210 views

How to design an enclosure around the load cell (Beam type)?

Hardware and Electronics Used: Arduino UNO, HX711 ADC Load cell amplifier, Load Cell (2Kg); Currently, I am working on a project which requires me to put load cell along with the other circuitry in an ...
2 votes
0 answers
35 views

Shape of a beam that is bowed under compression?

Suppose you have a uniform beam, such as a piece of plywood that is 4 feet long, six inches wide, and half an inch thick. Suppose you cause it to bend by attaching, for example, a string under ...
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Multiple varying cross section beam with distributed load - FBD Method?

Based on the 2 different threads read below : Multiple Varying cross section beam deflection + Multiple varying cross section beam with uniform loads I'm trying to set up a calculation sheet (Excel is ...
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3 answers
268 views

Confusion about sign of beam's moment force

A positive bending moment bends a beam concave upward(or towards the positive y direction), whereas a negative bending moment bends a beam concave downward(or towards the negative y direction). (...
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38 views

How much weight can aluminum square tube support?

I'm building a bed platform in a campervan and trying to determine what type of aluminum tube to buy. I'm thinking to purchase 6061-T6511 aluminum Square Tube with 1.5" width, 1.5" height ...
0 votes
1 answer
31 views

Need to Align Line Directions Normals Along Specific Coord in APDL

In Preprocessor of APDL, I have built areas which are meshed with shell element and lines meshed with beam elements. I have assigned Sections to Beam elements but when I view them their cross sections ...
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2 answers
55 views

Is bending stress over round thin-walled tube cross section linear?

It is thin walled because roughly d=200mm and t=6mm of a carbon fiber wrapped tube. The question is, if the bending stress $\sigma$ over the cross-section (in y-direction) is linear or not. It is ...
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2 answers
875 views

How can I understand shear flow in a beam cross section?

I am trying to understand shear flow and I am just not getting it. For example, one of the problems in Beer has an I-beam and there is both a horizontal and vertical force acting on it. So it has ...
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2 answers
971 views

Calculate shear and deflection for simply supported beam on different support height (like a staircase)?

I’m trying to calculate the beam deflection for an inclined beam. It’s only connected to floors (and not walls). The beam is a monorail and I want to test different shapes (tubes and I-beams). Plenty ...
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1 answer
39 views

Need to find beam deflection of a steel tube

So i have a square tube of 40mm, 3mm wall thickness with a length of 1 meter. Both ends are fixed 25mm inwards. Load is 3kg centerpoint. Steel is SJ235. I need to know the deflection of this beam. ...
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1 answer
471 views

MSC Nastran - BAR3/4 elements - can't assign any properties

I'm modeling a pipe in Patran, and I'd like to try bar3 and bar4 elements. I assing the properties CBEAM to my geometry, but when I create the mesh, Patran tell me bar3 and bar4 don't support that ...
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1 answer
296 views

What is the equivalent rotational/angular stiffness of a beam

I'm trying to model a larger system and working through a conceptual issue. I'm familiar with the concept of expressing the stiffness of a beam as an equivalent spring stiffness like in the image ...
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20 views

Sign convention in link

If we take the moment about A from the $F_{BC}$ will make the body want to rotate counter clock wise but If we take it from the point C it will make the body rotate clock wise whats the mistake?
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Uniform Direction for Line Directions

Despite several similar questions and my efforts, there is still no solution so far. Presently, ANSYS gives Directions to Lines on its own which are flipped even for two collinear lines. As a results ...
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2 answers
131 views

Shear Force in Inclined Beam

Suppose I have an inclined beam with a UDL applied vertically downwards, will the shear force act normal to the beam, or vertically?
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1 answer
65 views

Calculating Admissible Shear stress with a uniformly distributed load and a point load

I have the following equation for calculating the Admissible shear stress for a uniformly distributed load. $$\tau_{adm} = \frac{3}{2}\cdot \frac{F\cdot L}{2b\cdot h}$$ where $F$ = kN/m $L$ = ...
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Mass Brick Settling Causing Excess Load On Center Beam

I live in a 115+ YO building and recently had my kitchen remodelled. During this the subfloor was replaced (old 1x6s in bad shape). I noticed a significant bow in the joists with the central steel ...
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3 answers
154 views

Can the general Flexural formula be used in the case of transverse loading of a beam?

The general derivation of the Flexural formula uses the pure bending case, where the distance from a curved section to the neutral axis is assumed to be constant even after bending, denoted by y. The ...
8 votes
2 answers
1k views

Design of transverse reinforcement in a wide beam

Besides satisfying nominal bar provision in the code, is there any special requirement in the provision of transverse reinforcement to ensure that the longitudinal reinforcement is fully effective in ...
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1 answer
67 views

Determine the temperature required for expanding or bending?

Is there any possible way to calculate the temperature required for a metal to expand or bend with dimensions? For example, take Mild steel with a length of 100mm, width of 150mm, and thickness of 2....
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0 answers
47 views

Setting direction vectors for Lines in ANSYS APDL

I am using beam elements to mesh lines with "pre-meshed" shell areas. Problem is that the ANSYS sets Line Direction vectors on its own. This results in Cross sections assignment flipped from ...
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1 answer
185 views

Boundary conditions for a cantilevered Timoshenko Beam

I am trying to find out the boundary conditions for above given Timoshenko beam. The boundary conditions that I have derived are $x_1 = 0$ $$ \overline{u}_2^L = 0 $$ $$ \phi_3^L = 0 $$ $x_1 = \...
1 vote
1 answer
213 views

Beam stiffness matrix with sliding end release in arbitrary angle

I know how to get the stiffness matrix of a beam with any type of end releases (hinges and rollers) by applying Guyan reduction (static condensation) to the beam stiffness matrix in local axes. ...
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1 answer
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Beam deflection for FEA model validation

I'm trying to validate an FE model that I'm using by comparing to a simplified analytical solution to the problem. The part I'm analyzing is a lug that is constrained on one end and has a point load ...
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1 answer
241 views

Linear Motion Stage with Offset Loading Problem

I'm currently developing a linear motion system which will have to withstand a large offset load (see image below). There will be two rails, each with a carriage on, which will be connected by a beam/...
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2 answers
212 views

Composite Cantilever Beam Analysis

I'm trying to solve this composite cantilever beam for deflection analysis. How should I proceed? I'm not from mechanical background. The connection between the elements is strong enough that the ...

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