What is Beam: Definition and 1000 Discussions

An I-beam, also known as H-beam (for universal column, UC), w-beam (for "wide flange"), universal beam (UB), rolled steel joist (RSJ), or double-T (especially in Polish, Bulgarian, Spanish, Italian and German), is a beam with an I or H-shaped cross-section. The horizontal elements of the I are flanges, and the vertical element is the "web". I-beams are usually made of structural steel and are used in construction and civil engineering.
The web resists shear forces, while the flanges resist most of the bending moment experienced by the beam. The Euler–Bernoulli beam equation shows that the I-shaped section is a very efficient form for carrying both bending and shear loads in the plane of the web. On the other hand, the cross-section has a reduced capacity in the transverse direction, and is also inefficient in carrying torsion, for which hollow structural sections are often preferred.

View More On Wikipedia.org
Recent contents Top users
  1. S

    B How long is a beam of sunlight?

    How long is a beam of light or sunlight?
  2. tarkin

    What Forces Affect an Electron in a Particle Accelerator?

    Homework Statement [/B] Consider an electron beam traveling with velocity v. The total current of the beam is I.The beam is of uniform charge density and has radius R. (a) Find E and B at r<R and r>R using Gauss' and Ampere's laws. ( This part is fine.) (b) Consider an electron in the beam at...
  3. yecko

    Net forces versus net moments -- solving a beam problem

    Homework Statement Homework Equations in photos The Attempt at a Solution [/B] First approach: Second approach: The two approaches used net force and net moment respectively in order to find reaction force of O, yet they got different answers. Why? Thank you very much!
  4. D

    What is the Speed and Number of Protons in a Van de Graaff Generator Beam?

    Homework Statement A Van de Graaff generator is one of the original particle accelerators and can be used to accelerate charged particles like protons or electrons. You may have seen it used to make human hair stand on end or produce large sparks. One application of the Van de Graaff generator...
  5. B

    Calculate the maximum deflection of a simply supported beam

    E=220GN/m² L= 7m W= 20kN at 2m from the left edge. udl=10kN/m from x=2 to x=7Beam supported in x=0 and x=7 I am not sure ir this is the way to do it.
  6. J

    Beam Bending of a Linearly Varying Beam with 2 point loads

    I'm trying to design something and rather than solve it using FEA guess and check, I'm trying to mathematically solve it. The part I'm getting stuck at is having 2 point loads on a linearly varying cantilever beam. https://imgur.com/LtHCvCB The closest example I could find to this that was...
  7. B

    Gaussian beam spherical mirror reflection question

    Homework Statement Gaussian beam of radius R_i and beam width w_i, The beam is reflected off a mirror with a radius of curvature R = R_i and the reflectivity of this mirror is given as rho(r) = rho_0*exp(-r^2/a^2), where r is the radial distance from the center of the mirror and a is a...
  8. D

    Beam centering using a photodiode

    Hi all, I am a mechanical engineer so I'm hoping to get a bit of guidance on something I am working on at the moment. I am working on a project which requires we keep actively keep a laser beam centered on a mirror. The mirror transfers a small percentage of beam power and I am hoping to use a...
  9. L

    Effective Flexural Rigidity (EI) of Composite Cantilever Beam

    Hello, I am trying to derive the (Euler-Bernoulli) beam equation of a composite beam to determine the vibration and natural frequencies (up to 3 modes) of the beam. The composite beam can be modeled as in the picture below: In order to apply the general equation: (EI)effw'''' = m'eff...
  10. T

    Calculating Beam Load for One Way Slab: Analysis and Solutions

    Homework Statement In this question , i think the author is wrong . In the question , the author use 0.5nIx , i know it's for one way slab . P/ s : Photo 701-703 is for first case . Photo 704 to 706 are for 2nd case . Homework EquationsThe Attempt at a Solution But , i think the load from slab...
  11. U

    Lifting a Beam with a uniform weight distribution

    Homework Statement Hi There, I'm having trouble understanding (what I guess should be) a simple concept and so I can't apply it to a project I'm working on (also kind of rusty on torques and mechanics problems) If I have a hinged beam (of uniform weight) and I lift it from one end and stay...
  12. F

    Sign convention of fixed end moment at cantilever beam

    Homework Statement I don't understand why the fixed end moment at AE is 10KNm ( clockwise) . Homework EquationsThe Attempt at a Solution Forger about the sign convention here , i have the resultant moment = 10KNm , which ic clockwise , why in the 2nd picture ( SFD and BMD part) , the moment...
  13. M

    A Irradiance distribution of projected beam

    Hey folks, I'm having a little bit of trouble shaking the rust off of my radiometry. I'm projecting a circular beam of some known divergence and power onto a surface angled relative to the center of the beam. Say holding a flashlight, with a cone of half angle θ, at my waist some height h off...
  14. B

    Critically damped cantilever beam

    I need to design a multi-layer cantilever beam with alternate visco-elastic and elastic layers. The goal is a beam with 18" unsupported and 4" glued to a firm support. In operation, this firm support will be vibrating in the audio range and the beam wants to damp out those vibrations and not...
  15. P

    Is it possible to bend a laser beam?

    If so how can we do that?
  16. F

    Tower Crane Tie Beam and Anchor Design: Maximum Force and Tension Calculation

    Hello everyone http://imgur.com/kc2kV8V can you please take a look in the tie beam and anchor design from the link above as i could not upload the picture directly. https://ufile.io/6v7l1 https://ufile.io/6v7l1 i want to calculate the maximum force that this anchor can resist before failure ...
  17. R

    Simscape help -- make a beam tangent to eccentric axis

    hello everyone, I'm trying to model a system in simscape using the simMechanics blocks. The system I am trying to model is: a ball bearing connected eccentrically to a motor axis. On that ball bearing lays a beam. The edge of the beam is connected to an axis. so, the system looks like this: I...
  18. spareine

    Sketch of the electric field of a laser beam

    I am trying to sketch the electric field E in snapshot of a linearly polarized laser beam. Is it correct that the E vectors bend from vertical to longitudinal near the cylindrical surface of the beam, and that all field lines within a half wave segment are closed loops?
  19. Saracen Rue

    Second Order Differential Equations - Beam Deflections

    Homework Statement A cantilever of length ##L## is rigidly fixed at one end and is horizontal in the unstrainted position. If a load is added at the free end of the beam, the downward deflection, ##y##, at a distance, ##x##, along the beam satisfies the differential equation...
  20. Twigg

    Momentum density in a Divergent Beam

    For a divergent paraxial field like $$E = E_0 e^{-\frac{r^{2}}{w(z)^{2}}} e^{-i(kz - tan^{-1}(\frac{z}{z_{0}}))}$$ What is the direction of the momentum density of the E-field. I have two competing feelings about it. 1) The momentum density should be parallel to the Poynting vector, and since...
  21. T

    Identify the type of support at each location along the beam

    Homework Statement I have problem with the carried over factor in photo 670 . It's not stated the type of support at point A , B , C , D and E . But , at joint at A and E , it's fixed support because the author use distribution factor of 1 at A and E ( in photo 669) Homework EquationsThe...
  22. S

    Horizontal to tilted beam radiation

    Hello, the name's Mike and I'm a newbie here, I have a question pertaining to solar angles required to calculate a solar panel's hourly generation over one year. Total solar irradiance on a tilted surface equals the sum of the direct, diffuse and reflected component. In my case, reflection is...
  23. A

    Is My Solution for a Simply Supported Beam Correct?

    Hi, wondering if any can have a look a the below to see if my working outs are correct. Thanks. 1. Homework Statement Determine the two support reactions at positions ‘A’ and ‘B’ for the following simply supported beam which is acted on by a uniformly distributed load (UDL) and two point...
  24. U

    B Why is it harder to break tied spaghetti compared to separated spaghetti?

    Hi fellow members, I have one question for you that may seem basic and easy that is however concerning me: why when 3 spaghetti are tied together it is harder to break them than when they are separated by a certain distance? Thank you in advance! NB :Number of spaghetti and reparation don't...
  25. SirLollington

    Collimating a laser beam with a fixed focal point?

    Hey, Not sure if this is the correct sub-forum to post this question. I'm still kinda new here, so sorry if I got it wrong :smile: I have a laser module with a fixed focal point of 16 mm and I'm trying to collimate that light into a beam. The point of focused light is at most a quarter...
  26. A

    I Creating a Neutron Beam: Challenges & Solutions

    When an artificial neutron source is created, from decay (from ground state or from an excited state resulting from fusion or a photon), or spallation, the trajectory of the emitted neutron is random,right? This would mean that there would be a neutron flux field, following the inverse square...
  27. Fernando

    Two spots with one laser beam in images

    Hello everyone. I have a question about Optics and I place here because I don't know if there are a specific thread. I am using a laser beam to calibrate position of several cameras. But instead of to have one spot in the image I have two spot. One of them is smaller of the other. I presume...
  28. Feodalherren

    Vibration of a cantilever beam problem

    Homework Statement A rectangular cantilever beam of length L and side lengths b with negligible mass is attached horizontally to a wall. A mass m is attached to the end of the beam where a motor is also located. The motor applies a force on the end of the beam described by the equation...
  29. R

    Near solar mirror for beam propulsion and space solar power

    NASA just announced a solar probe to travel quite close to the Sun, about 3.7 million miles from the solar surface: Nasa’s hotly anticipated solar mission renamed to honour astrophysicist Eugene Parker. Renamed the Parker Solar Probe to honour solar astrophysicist who predicted high speed solar...
  30. thetasigma

    Tension in two ropes attached to a beam

    Homework Statement I have attached an electronic image of the problem to this post. The problem states that there is a beam (AB), which has length 5 metres and mass 25 kilograms. It also states the beam is suspended in a horizontal position by two vertical ropes. One rope is attached to the...
  31. eigenmax

    Electron beam energy to acceleration potential relation

    Hi, How can I relate the beam energy of an electron beam produced by an electron gun to the accelerating potential? I realize that accelerating potential, initial energy (before acceleation), and losses by synchrotron radiation, etc, will play a part. I searched online and can't find much. Thanks
  32. M

    B Question about a beam of light

    I can't understand this term. Specially a beam of white light. Is it a combination of photons or electromagnetic waves that moving in space with different wavelengths? Since output of a prism is analogous transition of colors that makes me think there are infinite number of wavelengths in...
  33. R

    Light beam propulsion without lasers?

    We now have the capability to do laser launch. The problem is the initial cost outlay for the lasers is still prohibitive to launch a sizable payload. The estimate of the payload you can launch to Earth orbit dependent on laser power is about 1 kg per megawatt. So to launch thousand kilo...
  34. O

    Cathode ray tube, Voltage needed to move the beam impact spot

    Homework Statement Question: A cathode ray tube in a TV has an electron gun operating at 10 kV. a: What is the velocity (in m.s-1) at which the electrons are emitted? Answer:5.9x107 b: How many volts are needed between the deflector plates to move the beam impact spot across a 70 cm screen if...
  35. H

    How are singularity functions used in beam analysis?

    HI I am going through an example on signularity functions. I don't understand how the author went from the line which I highlighted in blue to the line which I highlighted in red.
  36. Asmaa Mohammad

    The collimated parallel beam of a LASER

    Homework Statement Multiple-choice question: The LASER beam is a collimated parallel one, that means that its photons have the same... (i) phase (ii) direction (iii) intensity (iv) frequency Attempt at a solution I would exclude frequency because it has nothing to do with the fact...
  37. W

    How to calculate the tension in a beam of a bridge?

    Homework Statement A bridge, constructed of 11 beams of equal length L and negligible mass, supports an object of mass M as shown in the picture. Assuming that the bridge segments are free to pivot at each intersection point, what is the tension T in the horizontal segment directly above the...
  38. F

    Why are fixed end moments AB and BC not considered in this problem?

    Homework Statement In this problem , i don't understand why the fixed end moment AB and fixed end moment BC arent considered ? Homework EquationsThe Attempt at a Solution Is it because we are asked to find the moment at B , so only fixed end moment AB and fixed end moment BC arent considered ?
  39. F

    Understanding Fixed End Moments in Beams: AE vs EA

    Homework Statement I don't understand the fixed end moment AE and also fixed end moment EA ? shouldn't they be the same ? Homework EquationsThe Attempt at a Solution For the fixed moment AE / fixed moment EA , shouldn't it = -10(2) +5(2) = -10 , for fixed end moment , we always assume...
  40. N

    Can a Cantilever Beam with a 20 lb Mass Hold Up without Failing?

    What's happening Form, It's been a while since I've done a FBD, but I wanted to get someone's input here and tell me if my math/logic is correct. I want to install a cantilever steel beam with a 20 lb mass at the end of it. I'm using carbon steel ASTM A108 (cheapest steel on McMaster-carr). I...
  41. S

    Ultraviolet Laser Beam Shaping With Constraints

    Homework Statement Homework Equations Lens equation 1/f = 1/d_o + 1/d_i Minimum Gaussian beam spot 2*w_0 = ((4 * lamda * F)/(pi * D)) Where: w_0 = beam waist (half beam diameter) lambda = wavelength F = focal length of lens D = diameter of incoming spot Don't forget to match units. Let...
  42. F

    Moment in a Beam: Consider Both Spans AB & BC

    Homework Statement In this problem , why only caluclation of span AB is considered ? why the span BC isn't required ? Homework EquationsThe Attempt at a Solution I think there's soemthing wrong with the question , We have to consider the calcilation of span BC also
  43. bradk2fan

    Confused on a few things for a beam and cycles to failure

    I have a problem which is a beam with 2 machines on the beam and one of them has an operating frequency between 200 and 600 rad/s that transmits a force to the beam. I have to determine the number of cycles to failure of the beam. It's stated in the problem statement to account for the mean...
  44. F

    Moments -- sign convention in beam

    Homework Statement In this question , we can see that in teh second picture , the 12.86kNm is in clockwise direction at the right of span BC . Homework EquationsThe Attempt at a Solution In meachnic of materials , i learned that when the beam curve upwards ( U shape) , then it has positive...
  45. JEngineer

    Calculating Beam Sizing for Cargo Transport

    Good Day Guys, I need help in checking the beam size required to transport a cargo. What checks do i do? 1. Check actual BM with resisting moment of the beam 2. Check actual shear with the resisting moment of the beam How do i calculate following if I only know the type of beam used, i.e...
  46. F

    Carry over factor in beam calculation -- confusion

    Homework Statement I have several question regrading with this post . 1.) For BC and CB , we could see that it's far end pinned / roller supported , so , shouldn't be the K = (3/4)(EI / L ) ? 2.) I don't understand how the carry over factor works (in the second picture) Homework...
  47. Greg Bernhardt

    Chemical/Paint Paint bubbling off wood beam DIY help

    As you can see from the image a vertical portion of my wall (a wood beam) has developed this vertical bubbling where the paint is being rejected. It spans from the ceiling to floor. First thing I thought of was water damage, but as I chip away at the paint and get to the wood it doesn't seem...
  48. F

    Understanding Carry-Over Factor in Beam Analysis

    Homework Statement I don't understand why for the first case , the 0.4 and 0.6 is used ? for the second question , we can see that in the first case , the moment from BC is carried over to CB ( highlighted part - line 4 ) ... Why for the second case , the moment from BC (6325.8) isn't carried...
  49. EthanVandals

    Solving Balancing Beam: m1, L1, m2, L2

    Homework Statement In the picture, m1 is 20kg, and the wedge pushes up with a force of 300 N. If the length L1 is 2 meters, solve for m2 and L2. Homework Equations I'm not sure The Attempt at a Solution The picture shows some sort of beam balancing on a fulcrum that is not centered. On the...
  50. V

    Closed form solution for second order beam deflection?

    Homework Statement A beam of length L is fixed on one end and roller supported on the other end. An axial force P is applied on the ends of the beam. The beam is loaded with a uniform distributed load (q) along its entire length. The beam has constant EI. Find an expression for the maximum...
Back
Top