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.

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  1. JEngineer

    Forces transferred to beam and to supports from box

    Hi Guys, I am trying to calculate the load transferred on the beams and then to the four supports (two under each beam) from a cargo (in this case say a box) to be stored in a yard. I have to check the suitable beam to be used and the load transferred to each support. Thanks in advance. :)
  2. S

    Rotate only H-Pol Component of Light beam by 90 degrees

    Is there a single optical component that will do the following? Do nothing to the horizontally polarized input, but rotate the vertically polarized input by 90 degrees, so that both beams finally emerge with the same polarization? I am looking for a single element that will replace the...
  3. L

    Laser Beam Diameter which Minimizes Volume?

    Homework Statement Consider a 10 meter long gas column. We interrogate the gas molecules with a HeNe laser (lambda=633nm) at the minimum possible gas volume. If we focus the beam tightly, it will eventually diverge and the sampled gas volume will increase. Consider a minimum beam diameter D...
  4. A

    A How could we produce a secondary beam of long neutral kaon

    how could we produce a secondary beam consisted of long neutral koans using PS or SPS ? I mean is there any example of such an experiment? what are the conditions for conducting this such as the type of the primary beam, the type of the target and the momentum of the beam? I am interested to...
  5. S

    I Hong-Ou-Mandel with two beam splitters

    In http://ws680.nist.gov/publication/get_pdf.cfm?pub_id=104112 , Pittman et al write: Is it possible to make a version where the two photons pass through two different beam splitters altogether, but are brought together finally at the detectors? For example by slightly tilting the mirrors...
  6. Pakano

    Extreme focus of a radially polarized beam

    What happen if a radially polarized beam is extremely focused to a single spot? Is it disappeared because E-fields in opposite direction subtract each other?
  7. A

    Why are there modes in cantilever beam oscillation equations

    I'm doing an experiment measuring the relationship between length of a cantilever beam and period of oscillation when I twang it on one end, but I can't seem to understand the equation. The equation for measuring frequency is given here:https://www.hindawi.com/journals/amse/2013/329530/ but I...
  8. B

    Find beam stress in a beam with varying cross section

    Homework Statement Hi, I'm trying to figure out how to calculate the stresses in my beam. The cross section varies (shown in the picture), and I don't know how I'm supposed to think to find the maximum stress. I appreciate tips or links to learn how to do it. Thanks. Sorry if the picture is...
  9. S

    B Relative Speed of 2 Beam Lights: Is it C or Zero?

    here "c" is the speed of light , i have a question in my mind and i have no answer for it , if two light beams are moving in opposite directions then their relative speed is simply c using the law of velocities addition in case of special relativity but what if those two light beams are moving...
  10. Invutil

    I Shining a light beam back -- relativity

    According to the textbook, "In this case, you (A) and Jackie (B) no longer agree about her speed _relative_ to the speed of the light beam. She'll see the light beam pass by her at the speed of light, c, but you'll see it going only 0.1c faster than she is going." Illustration here, under "The...
  11. H

    Designing Haunch for Cantilever Beam in BS 8110

    Hi guys, how do I design the haunch for the cantilever beam? The slab area is relatively small, with 125thk ( 4.39m x 1190m ). I've looked through everywhere but I can't find on how to design the haunch. I'm using BS 8110. Thanks.
  12. saybrook1

    Analytical bending of a deformed beam

    Hi guys; I have an analytical solution for the deformation of a beam due to a couple with moments C_1 and C_2 with boundary conditions y=0 and x=±(L/2) where L≡length of the beam. The derivation from the Bernoulli-Euler equation is below: \begin{align*}...
  13. O

    Find Reactions to Overhanging Beam

    The question is: How do I find all the reactions? I haven't worked with a similar problem before, so I'm kinda confused. Hope someone will help! Thanks from now.
  14. F

    Stiffness factor for member in beam

    Homework Statement In this question , I don't understand why the KBC is 4EI / L ...Homework EquationsThe Attempt at a Solution I was told that for the far end pinned or roller supported , the K = 3EI / L , so shouldn't the KBC = 3EI / L.. Is the author wrong ? In the 3rd photo , we can see...
  15. saybrook1

    Measuring the deflection of a beam

    Hi guys, I have a set of 2-D data in excel, an X and Y column. The X column ranges from ±200 and the Y column is a Gaussian distribution ranging from about 6 to 12. In total there are about 500 data points. I need to normalize the data so that the Y column values have endpoints at 0 for X=±200...
  16. F

    Stiffness factor modification in beam

    Homework Statement In this question , the author use only the left section of the beam for analysis ... How can we just consider a part of the beam for analysis ? We must consider the whole beam , right ? And find the KCD also . Second question , why there is no need to use carry over factor...
  17. F

    Conjugate Beam M/EI: Explaining Diagrams & Theorem

    Homework Statement I don't understand how the diagram of M/EI of conjugate beam drawn , can someone explain about it ? According to conjugate beam theorem , Homework EquationsThe Attempt at a Solution i know that the M/EI represent the w(x) , which is force per unit length of the beam . I...
  18. AdrianMachin

    Laser Pointer Troubleshooting: Solving Incoherence in a Red 650nm <5mW Beam

    I have a red 650nm and <5mW LASER pointer, but the beam is not very coherent. Actually, when I point to a wall at an approximately 300 meters away, the red point gets very large (about a meter in diameter). I wonder how a LASER could act like this?
  19. F

    Moment in beam (caused by influence line)

    Homework Statement http://cereference.com/book/structural-analysis/influence-lines-beams In the example , i don't understand the moment in the part of beyond AC . I don't understand why we don't have to consider the momenty due to unit virtual load in the part beyond AC , just like what we did...
  20. F

    Shear force in influence line of beam

    Homework Statement why at C . the shear force V change from -0.5 to 0.5 ? We wantg to determine the shear force at different location , and a unit force is applied at arbitary location ( measured from A) ... Homework EquationsThe Attempt at a Solution IMO , there's no upwards force of 1...
  21. S

    Ansys Workbench - Beam 188 and Link 180 element - together?

    Using : Ansys Workbench 16 Educational I want to build simple frame and simulate stress state and deformation when that frame is lifted. I have constructed my geometry in Design Modeler using line body's. My lifting cable has circular cross section with diameter of 10 mm. My frame has square...
  22. F

    Understanding Moment Distribution in Beam Analysis

    Homework Statement For the circled part , i don't understand why it's 4 and 6 . I know that it's about distribute the moment according to the ratio that we have determined earlier . Homework EquationsThe Attempt at a Solution For 4 , shouldn't it be 240*0.4 = 96 ? For 6 , shouldn't it be...
  23. F

    Angle of rotation in fixed end of beam

    Homework Statement In the first photo , i was told that the fixed end moment is zero when the far end is pinned or roller supported . Why in the example in the second and third photo( both end are fixed) , the angle is zero ? Homework EquationsThe Attempt at a Solution I think it's wrong ...
  24. CricK0es

    Torque, beam, angular acceleration problem

    Homework Statement [/B] A thin, uniform, 3.8kg bar, 80cm long has two 2.5 kg balls glued on at either end. It is supported horizontally by a thin, horizontal, frictionless axle passing through its centers and perpendicular to the bar. Suddenly the right hand ball becomes detached and falls off...
  25. F

    Slope deflections method analysis of beam

    Homework Statement why we need to consider 2 conditions , the beam curve downwards ( as in 11-3) and beam curve upwards ( as in 11-4) ? What's the difference between 2 cases ? I notice that in both cases , the author assume clockwise as positive here are the 3 consecutive pages of notes...
  26. F

    Slope deflection method for indeterminate beam

    Homework Statement In the link at 12:35 , the author show the equation of the displacement of the beam without explaining , can someone try to explain why we need to use 3 Φ , 2EI / L , 2θa and 2θB ? I have no idea at all . Homework EquationsThe Attempt at a Solution
  27. F

    Moment about a point on a beam

    Homework Statement For the moment about B ' , why there is extra θA L behind ? 2. Homework Equations The Attempt at a Solution is that wrong ? I think there should be no θA L behind in the equation of moment about B '
  28. M

    Help Needed with basic Beam & Structural Calculations

    Hello, My name is Molly. I am looking for help with Basic Engineering Calculations and how to understand them. This is not homework and certainly not for anything dangerous or anything I am building. I simply have developed a fascination for the subject and a strong desire to understand the...
  29. C

    How to code ultrasonic beam propagation

    Does anyone have an open source code or know how to code propagation of multi gaussian beams through multiple interfaces using the ABCD matrix approach? And this is using ultrasound and not optics. Please let me know if anyone can help out in this
  30. F

    Shear stress at the boundary of beam

    Homework Statement We all know that $$\tau = VQ/ It $$ how to determine the shear stress at **G** ? I'm having problem of finding Ay centroid if the solid that i found earlier is y = 98.5mm There's a dashed line from G to the bottom . It's making me confused . for Q , should i consider the...
  31. N

    Beam Divergence from non-circular laser beam

    Homework Statement The laser beam is not a point source. It is known that it has a rectangular shape with a divergence of 30 mrad x 1 mrad. I would like to know how large my laser lobe will be at a distance of 250 mm from the laser source. Homework Equations I think you can use trigonometri...
  32. C

    A Can a simply supported beam be a cylinder?

    I have an application where I am trying to figure out the shock load being applied to a metal pin (load cell). It is a cylindrical load cell which is supported at either end, and compressed in the middle. There is a slight gap between the end supports and the section compressed in the middle...
  33. N

    How does a Triple Beam Balance work?

    so I understand that it balances both sides of the scale but why does it have to be horizontal? in other balancing systems the beams do not have to be horizontal but in this system they do. I know it has to do with torque but can't seem to understand how the balance can be close to the right...
  34. D

    Will my PA66 (Nylon) beam plastic deform?

    Hello, I have this model that required to be pressed vertically 1mm. I successfully displaced 1mm vertically with 30N of force. Unluckily, Von mises stress goes way beyond the yield strength. However, the strain is below the yield strain of 5%. I do not understand how ductile/flexible material...
  35. schplade

    Beam-powered propulsion - keeping the beam focused

    I've often read that beam-powered propulsion is the only basic interstellar propulsion concept without physics problems. To me, that doesn't seem far from the truth. However, for a long time I've felt that the biggest obstacle to overcome is the beam divergence problem. Most of the concepts I've...
  36. J000e

    Understanding Maximum Moment for Moving Loads: Strength of Materials Reviewer

    Hey guys, I've been reading my strength of materials textbook and its pretty much like a reviewer that contain several problems and short descriptions of their concepts. There's this formula that computes the maximum moment for two moving loads and its: [PL-(Psmall)(d)]^2/4PL where P= Psmall...
  37. F

    Maximum slope of deflection of beam

    Homework Statement why the author said that by inspection , the maximum slope occur at D ? How do we know that ? He didnt show the working and explanation . Homework EquationsThe Attempt at a Solution If I consider the maximum slope to occur at a point after 2m from A , then i will take...
  38. SunRay-dvsh

    Oscillating Electron Beam potential between metal plates

    Take the case where the electron-beam is oscillating between two parallel metal plates, there will be alternating potential developed between the plates as metal tries to negate all external electric fields. My query is, (1) How to calculate the potential developed and possible way to simulate...
  39. A

    A Euler beam dynamic equation under point load

    Hi So the problem I have is I want to get the equation of motion of a vibrating beam under a nonlinear "Point" force. The equation would be like this for a distributed load (Which is not the case) But I want the load to be at a point at x=L So I have to options. Add an impulse dirac function...
  40. F

    Shear stress at different points of beam

    Homework Statement i'm not sure how to calculate the shear stress at point F and point G . I know that shear stress has formula of $$ \tau = VQ/It $$ The maximum shear force that i calculated earlier is V = 205kN , Ixx = 2.1x10^-4 for Q at $$\tau$$ at F , i have...
  41. F

    Moment applied causing bending stress in beam

    Homework Statement From the solution , it's clear that the top part of the beam undergo tension , while the lower part undergo compression . Homework EquationsThe Attempt at a Solution But , i don't understand why it is so . When the moment is applied in the horizontal axis , the structure...
  42. F

    Shear force at different parts of beam

    Homework Statement i know this question can't be done(since the location of point where the tau 1 and tau2 are measured are unknown) , but i want just want to check whether my concept is correct or not . we know that the shear stress has formula of $$\tau = VQ / It$$ , the question want the...
  43. F

    Determine forces in beam with hinges

    Homework Statement Is it possible to find the VA , VB and VC without ' breaking ' the beam into 2 parts ? Homework EquationsThe Attempt at a Solution Here's my working , i gt Moment about A = 10(1) -VB(2) -VC(4) +5(3)(4 + (3/2) ) = 0 Hence , 92.5-2VB -4VC= 0 moment about B = VA(2) -10-VC(2)...
  44. F

    Slope of deflection of beam at center

    Homework Statement in the first photo , it's stated that the dy/dx at center = 0 , however , in the second photo (website) , it's stated that the dy/dx at the boundary = 0 ,which is correct ? I'm confused now http://www.geom.uiuc.edu/education/calc-init/static-beam/support.html Homework...
  45. F

    Calculating Beam Deflection and Slope Using the Moment-Area Method

    Homework Statement Find the deflection and slope of bending of beam Homework EquationsThe Attempt at a Solution [/B] Here's my ans , but the ans given is EIy = -4953 , but i gt EIy = -5078 , anything wrong with my answer ? for slope at A , i gt EI(dy/dx) = 0 instead of EI(dy/dx) =625
  46. F

    Maximum deflection / slope of beam

    Homework Statement As in the diagram Homework EquationsThe Attempt at a Solution For part a ) , my ans is EI(d2y/dx2) = - Px For part b) , my ans is EI(dy/dx) = -P(x^2)/2 +c1 EIy = -P(x^3)/6 +c1x +c2 at x= 0 , y = 0 , so c2 = 0 , at x = 0 , dy/dx = 0 , so c1 = 0 , so , EIy = -P(x^3)/6 ...
  47. F

    Calculating Shear Flow in a Hollow Beam: Understanding Mistakes in Dimensioning

    Homework Statement for shear flow at D , the Q = Ay , i tried another method , i gt 30000 , instead of 29750, why the ans is different from 29750? why can't i use this method( i break the shaded area into 3 parts ( as shown in figure) Homework EquationsThe Attempt at a Solution Q = Ay =...
  48. Hercuflea

    B A light beam that never interacts with matter

    I have read that infinite time dilation goes hand in hand with infinite length contraction for photons. AKA "photons do not experience time", or from a photons perspective, it takes no time to arrive at its destination. What if you were floating in space with a laser pointer, and you pointed...
  49. M

    Calculating tension in a wire holding beam against wall

    Hi, this is my first forum post - sorry if I'm in the wrong place, or I've done something wrong! Homework Statement Here goes: There is a beam of 0.5m length hinged to a wall at a right angle with 200N mass at the end of the beam. This is supported by a wire T at angle 30°. The question asks...
  50. T

    How to find the FWHM-diameter of the SH beam?

    Homework Statement Assume a Gaussian laser beam ( 1064 nm wavelength) having an FWHM-diameter(intensity) of 5 mm. By transmission through a thin nonlinear crystal, a new wave is generated that is proportional to the square of the incoming field (and therefore radiates at twice the frequency, or...
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