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Questions tagged [beam]

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

362 questions
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Determining stiffness of a beam w/varying moment of inertia

I need to calculate $K$ or equivalent stiffness of a beam that has a varying $I$ across its length. $I$ has been given to me as a function of $x$, or length. I have been unable to find a proper equation or set of equations describing how to obtain…
Jacob Norman
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Is a force to the right positive?

I am trying to do this question and I have everything but one. Solving for $A_x$, $x$ force at $A$. $$\begin{gather} F_x = 6\cdot20 + A_x \\ A_x= -120\text{ kN} \end{gather}$$ Is this correct? Sign normally doesn't matter, if you're consistent,…
weeeeeee
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Axially Distributed Load

Given a beam ($\rho, A, l$) rotating with angular velocity $\omega$, find the maximum stress in the beam and its location. I think the maximum stress occurs at the base, because the resultant force is the entire axial force. The total axial force…
Beamy
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strongest way to join ibeams at angle

I have a stock of surplus i-beams (aluminum) and am trying to build a structure where they are not always parallel. I understand i-beam is designed to be aligned vertically and optimized for strength in that direction. What is the strongest way to…
stackzz
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Why two identical beams without being pinned together will share half of the bending moments?

As shown above, two identical rectangular beams are placed and NO pinned together. I know each beam has its own neutral surface but why they carry half of the bending moments? I thought the bending moments they carry are same because each of the…
iamyourmother
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How do I calculate kg/m for 5 boards sitting on 3 beams

I'm new to this, thank you for your patience, I have some wooden boards that each weigh 5.5 kg with dimensions of 120 cm * 60 cm I also have some wooden beams with dimensions of 3 meters length and 10 cm width (and 3 cm thickness) I want to know…
user2263572
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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 differential equation $$ \frac{\partial n}{\partial x_1} + \frac{\partial…
Ali Baig
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Deflection and stress in a freely rotating beam

How do I calculate the deflection and stress of a beam that is rotating freely (for example in space) when a moment is being applied to it, for example by rocket motors at the ends of the beam?
Beacon of Wierd
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Can bending moments for a combination of loads on a simple beam, be calculated by adding the individual B.M. of each load?

This problem is about bending moment of a simple beam subject to a mixture of 4 or 5 UDLs and point loads. The beam is assumed to be rigid enough that deflection of the combined load is "small". Solving this analytically for all load combinations…
Stilez
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Beam Span for Outdoor Shelter

I'm building an outdoor shelter and I'm wondering what would be: The maximum beam span for the type of wood/material used such it can support the roof weight and not sag in the middle, Suggestions on other materials (beams or otherwise) or…
Micah B.
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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 1/3 or 2/3 of the total length, What's the logic…
Thejeswini S
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Shearing Stress in a Beam with Torsion

In "Theory of Elastic Stability" by Timoshenko and Gere, the authors say for a beam in pure torsion, For a beam of thin-walled open section it can be assumed with reasonable accuracy that the shearing stress at any point is parallel to the…
Mark
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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). (source) Excuse me if the question is so simple, but in…
user134613
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Moment equilibrium equation of beam

The above beam is loaded by a distributed load per unit length of the referential scale defined by the vector field q = q(x) and a distributed moment load vector per unit length m = m(x). As a consequence of the external loads, the beam is deformed…
user134613
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Beam for shop gantry

I have a small machine shop and need to size a beam for a gantry crane. The design is a 4 post fixed design with 2 horizontal beams running parallel across the shop ends with 1 beam to be mounted perpendicular on trolleys on top of the two parallels…
Joe howell
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