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. L

    Where does the equation for Gaussian beam divergence come from?

    For a Gaussian beam, which has 86% of its power within its beam diameter (spot size 2w0), I've read that beam (angular) divergence is given by 2θ = 4λ/(π[2w0]) Where does this come from? I hate memorizing equations. It makes me feel stupid.
  2. P

    Deflection in a Simply supported beam

    Hi All As shown in the attached image, I have a simply supported beam with a load of 150kN acting at the center of the beam span. E = 210 GPa rho = 7800 kgm-3 span = 250 mm After solving this in FE solver, I got maximum displacement to be ~4mm (at node 52) But, on using the theoretical...
  3. S

    Pin and cable supported by a beam

    : Homework9-7 http://physci.kennesaw.edu/images/hm12-1.gif 1. A uniform beam of mass m is supported in a horizontal position by a pin and cable as shown in the Figure. Given. m = 20.0 kg ; M1 = 54.0 kg ; M2 = 37.0 kg ; L1 = 2.90 m ; L2 = 5.40 m ; and θ = 43.0°. a) How many forces are acting on...
  4. T

    Finding Tension in a Beam Supported by a Pulley: Solving for Equilibrium

    Homework Statement [Ans: FA = -206i + 188j lb, T = 131 lb] Homework Equations Since it's assumed that the system is in equilibrium, so I assume that ΣF=0 and ΣM=0 The Attempt at a Solution I tried to draw a free-body diagram for the system, and set up three equations below: (I don't know...
  5. D

    How to find cross sectional dimension of beam

    Homework Statement If the electric motor of problem 3.66 is to be mounted at the free end of a steel cantilever beam of length ##5## m and the amplitude of vibration is to be limited to ##0.5## cm, find the necessary cross-sectional dimension of the beam. Include the weight of the beam in the...
  6. D

    Find the mass and density of a beam

    Homework Statement I have a steel cantilever beam of length 5m, width 0.5m, and thickness 0.1m. The beam has uniform density. Homework Equations \begin{align*} M &= \iint_D\rho(x, y)dxdy\\ \rho &= M/\ell \end{align*} The Attempt at a Solution If I don't know the mass or density, how can I...
  7. K

    Off-Axis Mirror Collimated Beam Contour

    When you collimate a point source using an off-axis parabolic mirror (OAP) with a circular shape, the beam area of the collimated light becomes more and more elliptical (x-dir. is smaller than y-dir.) as the off-axis angle is increased. Is there a reason why this happens? And is there a way to...
  8. D

    Stress in a hollow beam bent laterallly

    I would like to calculate the maximum stress in a hollow beam being bent laterally. There has been some discussion in my office about the correct way to view the system in question, and so would like some other opinions on the matter. I will include pictures below. In simplified terms, the...
  9. W

    Indeterminate static beam loading

    Hello I am creating a torsional testing rig for a Formula Sae car, the front of the car will be pivoted about the center on a beam with the loading off to one side. In the design I need to calculate the deflection of the beam in order to determine which material and what profile of metal will...
  10. E

    Beam splitting experiment with single photon

    Consider the above experimental setup. Here the source can emit one photon at a time. The output from the source is sent to a beam splitter which divides it into three possible paths of equal probability. Splitter 2 further splits the path 3 into two paths of equal probability. We have...
  11. P

    Measurement of irradiance of 2 beam interference

    Hi, I have an experiment set up to get two beam interference fringes. I would like to know how I could measure the actual amplitude of the irradiance from the experiment. I have with me a power meter and a CMOS camera. How can I go about this? Thank you
  12. SteliosVas

    Maximum Bending Stress in Cantilevered Steel Channel Beam

    Homework Statement Okay this is the problem I have: I have a Steel Channel beam which has an cross sectional height of 300mm. It is 150mm in depth. Its wall thickness is 20mm. This beam is 6meters long as has a 10kN/m UDL applied. It is fixed at one side and unsupported at the tip. I have...
  13. D

    How Do You Calculate the Waist Radius and Location of a Gaussian Beam?

    https://www.physicsforums.com/attachments/73840 This is the problem I don´t understand, I know I hace to determine the distance z1 which correspond to the widht W1, but I try to solve equation of W1 and W2 for z1 and use the fact z2 = z1 + 0.1m, but I, my question is how to determine the waist...
  14. C

    Hinged rigid beam vs mass free fall

    Our test group had some issues with an ASTM foam cushion drop test, and I was asked to investigate. I fixed the problem, but noticed something in a high speed video. A 50 kg mass on the hinged platform separates from the platform when the raised end of the platform is dropped. I thought the...
  15. R

    Beam problem finding max bending stress

    Alright so I drew it out like did the reactions and everything then I realized I need to include the diameter of the beam. How do I find the max bending stress while using the diameter of the beam? All I need to know is what exactly I do differently compared to drawing the bending moment...
  16. C

    What is the significance of r in the intensity formula for a Gaussian beam?

    Hi!. I´m modeling a gaussiam beam. I found that considering the electric field distribution of Gaussian laser pulses along the axis of propagation, we can write the intensity as: Where y = I_l R is the power is the power reflection coefficient y = w_0 is the beam waist radius at y = z=0...
  17. B

    Help with beam deflection problem

    I need help with this beam deflection problem for 1 the book my professor gave me almost everything is hand written including the beam stuff... SO I can't read it at all and its really frustrating trynna do this without being able to read the formulas or anything please helpp! I attached the...
  18. W

    Bragg-scattering angle from scattered beam of energy

    Homework Statement A beam of thermal neutrons emerges from a nuclear reactor and is incident on a crystal as shown in the figure below. The beam is Bragg scattered, as in the figure, from a crystal whose scattering planes are separated by 0.253 nm. From the continuous energy spectrum of the...
  19. S

    MHB Explaining the Formula for Beam Strain: Motivating \epsilon

    i am working on the beam theory. where i have to consider a pure bending of a beam. they question asked was i should motivate the formula for strain \epsilon and use a setch to explain. how do i motivate the formula
  20. S

    Schrodinger wave eqn for a beam of monoenergeticc electrons

    The problem is to apply Schrodinger wave equation to a beam of mono energetic electrons and show that the probability of finding electron at each point on the beam is constant (d2ψ/dx2) + (8∏^2m/h^2)(E-V)ψ = 0 I have been taught to apply this to a single particle for various...
  21. Chacabucogod

    Mechanics of materials beam Problem

    A 1-ton wall hoist consists of a horizontal beam, supported by a tension rod at 30 deg, as shown. The rod is to be designed with a factor of safety 5 with repeat to its yield point of 30,000 PSI. Determine its necessary cross section S=F/A 30000/5=6000PSI -2000+Rsin(30)=0...
  22. D

    Calculating Bending Stress & Moment of Inertia for Tapered Cantilever Beam

    Hello all, I need to calculate the bending stress of a tapered cantilever beam. However, I would like to know how to calculate the moment of inertia. For a uniform shape beam, I know the Ix=(bh3)/12, but since h changes throughout the length of the beam how would inertia, I, be...
  23. Delta2

    Exploring Microwave Beam Width: Frequency's Impact on Minimum Size (50GHz)

    I guess we all know laser beams. I wonder if we can make beams in the microwave frequency range and how the beam width relates to the frequency, e.g what is the minimum beam width we can achieve with a frequeny of 50Ghz.
  24. D.R.U

    Balance Beam: Why Does It Stay Horizontal?

    I have already balanced beam both side two same mass at same distance and it is pivot on its center of gravity...so torque is zero so no rotation possible by gravity on earth......so why beam always be horizontal to Earth surface...after give inclination to Earth surface.....potential energy not...
  25. S

    Cantilever statically indeterminate beam with point load

    hi please if anyone can tell me how i can get the following equation (attachments) of deflection for statically indeterminate cantilever beam with point load (attachments). I'm not an engineering student and having difficulty in coming up with boundary conditions. looking for help. thanks
  26. medeek

    Residential Structural Engineering: Beam Calculator for Sawn Lumber

    I've recently started doing a lot more residential structural engineering for local clients and the first thing that I realized was that I was lacking a good beam calculator. I do have a number of spreadsheet calculators but I've found them hard to program and once I do have them programmed...
  27. N

    How Can Strain Be Calculated from Force Displacement Data in a Cantilever Beam?

    Hi everyone. I feel there should be a simple answer to this but I can't seem to find anything on this. So I have a simple cantilever beam, supported at one side and loaded at the free end. I have the force displacement data and can easily calculate the stress. However, for the strain I do...
  28. B

    Deflection of fixed beam with point load at center

    i have a 20.5ft c3x5 steel channel with a point load at the exact center and i wanted to determine its maximum deflection. the point load is 921.86lbs, and moment of inertia is 1.86in^4. modulus of E= 30,000,000psi
  29. D

    How to Calculate Safety Factor for Beam Columns?

    Beam held up by two columns I apologize in advance if you think this should really go in the homework help area, I am not sure because this isn't a homework problem, but rather my struggle to understand and carry out concepts. If it needs to be re-posted, or moved, I understand. :) In a...
  30. T

    Free electron beam inducing an EM field in a target?

    Consider the following experimental setup: the front half of a klystron tube (the electron gun and resonent cavity) or perhaps a free electron laser, several different targets consisting of a highly conductive(metal) object, a possibly conductive object(salt or clay), and a non-conductive...
  31. I

    Does a light beam bend in an accelerating elevator?

    My understanding is that a light beam will bend in an upward accelerating elevator. I told my uncle this. He responded that the velocity of the elevator cannot be added to the velocity of light since light's velocity always remains the same no matter the motion of the source or the observer...
  32. T

    Using magnets to hold an object in place on a large timber beam.

    I am a lighting designer for tv shows and I have a problem with a location that has very low ceilings and 22" timber beams running the width of a 30ft room. The location is a listed/heritage building and therefore we cannot cause any physical damage to the property including the ceiling. I...
  33. L

    Beam bending of an angled flat plate

    Hello everyone, I am wondering how to properly go about calculating the stresses caused by bending on an angled flat plate. Two approaches seem valid but they give much different results: -Calculate the new area moments of inertia for the angled flat plate (new Ixx, ymax)...
  34. Greg Bernhardt

    Understanding Gaussian Beams: Definition, Equations, and Parameters

    Definition/Summary A Gaussian beam is an electromagnetic wave, usually a laser beam, with a Gaussian cross-sectional irradiance pattern. The Gaussian irradiance profile results in minimal spreading due to diffraction effects. The spot size w represents the radius or half-width at which the...
  35. B

    Bending Moment of a Cantilever Beam

    This is a problem from Michael Lindeburg's FE Review Manual. It is in Chapter 20, Number 11 if you have the book. PROBLEM: There is a picture of a cantilever 2 m in length attached to a wall. There is a force applied at a 30 degree angle from the horizontal at the free end of the beam...
  36. Tranceform

    Relative Velocity of Two Objects Moving at Different Speeds

    Homework Statement An intergalactic cruiser is approaching a hostile spacecraft . Both vehicles move at a constant velocity. The velocity of the cruiser relative to the spacecraft is vCS=+0.7c, the direction to the right being the positive direction. The cruiser fires a beam of laser light...
  37. N

    Laser Beam - Divergence and Solid Angle

    I am somewhat confused about the connection between divergence and solid angle for a beam. I know individually what each term means... but I'm confused as to how (or even if) one can calculate the solid angle of a beam, given the divergence. I have some notes from a previous lecture series I...
  38. E

    Analyzing a Beam with One Degree Freedom in ANSYS APDL

    hi every body I want to analysis a beam with one degree freedom on apdl (ansys software) This software give me a different period! for beam with mass=stiffness=1 we must have 2π value for period but this program give me another answer.
  39. C

    Questions about current limits of laser beam widths

    Hi there, I'm looking for some information on the current limits of the beam width of currently available lasers. I'm less interested in experimental setups that are not on the market yet, but I suppose if one of them is markedly different it would be interesting to know. Specifically...
  40. karush

    MHB How fast is the lighthouse beam moving along the shoreline?

    A light in a lighthouse $1$ km offshore from a straight shoreline is rotating at $2$ revolutions per minute. How fast is the beam moving along the shoreline when it passes the point $\frac{1}{2}$ km from the point opposite the lighthouse? ok we have a right triangle where the $\theta$ is the...
  41. P

    Calculating Stresses on Bent Aluminum Beam: Experiment Results

    I am performing an experiment for my project. I have bended an aluminum beam of 1in by 1/4 in by 14 in (Al 6061 T6). I deflected the beam upto 0.09 in at the middle. I need to find Sigma x, sigma Y and Shear stress on the expanded and compressed face of the beam which is 1 in by 1/4 in. Can...
  42. S

    Fully restrained beam moment diagram

    Homework Statement Find the shear and bending moment diagram for a fully restrained beam with a length of 5m, a uniform distributed load of 1kN/m from x=0 to 2m, a point load of 1kN at 2m, and another uniform distributed load of .9kN/m from x=2, to x=5. Homework Equations The...
  43. M

    Making a 50 um collimated beam on a budget

    Hello again, My handy optics engineer has left the country leaving me with a problem that's over my head. I need a low cost (i.e. $500.00) solution to produce a circular, collimated, 405nm beam. My beam needs to be within the target diameter (+/-20%) from 0 - 4" from the output lens and...
  44. naima

    Characteristics of beam splitters

    I read that there are polarizing and non polarizing beam splitters. Are there adjustable bleam splitters between them?
  45. J

    Calculating the Radius of Curvature for a Deflected Beam

    Hey Guys, I'm stuck with this problem, we want to compare the curve of a beam to it's horziontal deflection, it's for an experiment we're performing on a very elastic beam. In the attachment you see a flexibel beam getting deflected by a force, this causes displacement x. We don't know (or...
  46. K

    Is tesla death ray ( death beam ) exist ?

    i wonder about tesla death ray. is this machine really exist ? or just conspiracy theory ?
  47. A

    Simulation of a Gaussian beam in an optical waveguide

    I am trying to simulate a Gaussian beam through an optical waveguide having a circular cross-section in matlab. I am familiar with the theory of modes in an optical fiber and can analytically calculate the evolution of the beam by breaking down the beam into a sum of infinite modes. However, I...
  48. G

    Differential equation to describe beam width

    I have two independent variables (rotation in degrees, and distance from best focus distance in mm) and one dependent variable (1/e^2 width squared in mm^2). How would I go about creating either a multivariable function or a differential equation to describe the data? I've attached the raw data...
  49. N

    How hard would it be to output a stable beam if a certain wavelength?

    I want to output a specific wavelength of infrared light, I believe the wavelength was 9.25nm, how hard would that be and how would I proceed?
  50. R

    L (Angle) & C (Channel) beam sections versus an I section

    In terms of unit material spent my impression is that an I beam uses it most efficiently at least for non-torsional loads? i.e. putting most material far from the axis into the flanges giving higher moments. If so, what are situations when an angle or channel cross sections are preferred in...
Back
Top