What is Bridges: Definition and 41 Discussions

A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually something that is otherwise difficult or impossible to cross. There are many different designs of bridges, each serving a particular purpose and applicable to different situations. Designs of bridges vary depending on factors such as: the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, and the material used to make it and the funds available to build it.
The earliest bridges were likely made with fallen trees and stepping stones. The Neolithic people built boardwalk bridges across marshland. The Arkadiko Bridge (dating from the 13th century BC, in the Peloponnese) is one of the oldest arch bridges still in existence and use.

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  1. S

    Engineering Understanding stress analysis of truss bridges

    Hi im trying to understand truss bridges. Where would max stress be in single span truss bridge if it was evenly loaded across the bridge? I thought single span truss bridge, max stress would be in the ends of the bridge. it would act like a simple supported beam with max bending motion being...
  2. D

    I Einstein's 1935 Paper on Wormholes & Modern Physics

    Does anybody know why Einstein never pursued the idea of wormholes beyond his very short 1935 paper? If he did does anybody know of any of his papers that go into this idea in more detail. I know recently there was the proposal of EPR=ER mainly put forth by Susskind and Maldecena. The ER=EPR...
  3. C

    Strain gauges and Wheatstone bridges

    Anyone know the significance of strain gauges and Wheatstone bridge in applications within mechanical and robotics areas. Thanks
  4. jaumzaum

    Do we need salt bridges in Electrolytic cells?

    I was wondering if we really need salt bridges when doing Electrolysis. I would answer yes, because we need to neutralize the charges in both sides, or the potential difference of the Electrolytic cell will keep increasing until the generator that is connected to it is not able to supply any...
  5. T

    Bridges: Exploring the Strength of Shapes - Arch vs Truss Design

    So triangles are apparently triangles are the best shape to use in bridges... But why? I'm pretty sure that a circle or even an arch is stronger than a single triangle. So is it possible to combine circles or arches on a bridge like how a truss design combines triangles?
  6. J

    Replacing ATV Trail Bridges: Cat 259D Skid Steer Impact

    A local ATV (All Terrain Vehicle) trail has some bridges over wetlands. The original supplier of the wood decking did not properly pressure treat the wood, so several of the bridges are being replaced. One bridge had the decking replaced last year. The contractor replacing the other bridges...
  7. 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...
  8. Natalie456

    Salt Bridges in Cells: Voltage & Distance

    I know that salt bridges maintain charge, thus allowing the reaction to proceed. I was wondering if the distance of the electrodes from the salt bridge affects the voltage of the cell in any way. Thanks!
  9. B

    I Why do bridges freeze before roads?

    All across America there are signs on bridges that warn motorists that bridges freeze before the roads. What the signs mean is that the road that is a bridge freezes before the parts of the road that are not bridges. I believe that the reason that bridges freeze before roads involves...
  10. C

    Other Switching Research Groups Without Burning Bridges

    I am seriously considering switching research groups. To be brief: I am a graduate student in condensed matter physics who had just passed the PHD candidate qualification exam. I have been working in my current lab for a year. I am unsatisfied with my working conditions in terms of interactions...
  11. M

    How does curvature of an arch bridge affect its strength?

    Hey, I've been looking into some civil/structural engineering for a school project, and came across bridge design. I've decided to try some integrating and optimising to do with an arch bridge (optimal cost/strength proportions). The math isn't too hard, but what I'm struggling with so far is...
  12. C

    Searching for the Density of Manila File Folder - Help Needed!

    Homework Statement Hi! I wasn't sure how to ask this, but my team and I are making a manila file folder bridge and we are stuck a specific part. We are looking to get the mass of the members and we decided to get it through multiplying the volume of the member by the density of manila file...
  13. Domenico94

    Understanding Equivalent Impedance in a Bridge Circuit | Homework Help

    Homework Statement Hi everyone, I'm just having a little trouble with equivalent resistance in a bridge, in the image I attached. The textbook says that the way to solve this is to put R3 and ZL2 in series, that series is in parallel to the short circuit in diagonal, and then at the end we...
  14. patrickbotros

    Galvanic Cells and Salt Bridges

    I went to class and watched this video () but I still don't understand how salt bridges work. I think I memorized all of the details and steps but I don't understand why anything is happening at all! I know that Cu2+ gains two electrons when it touches the electrode but why? And also does the...
  15. D

    Technique to avoid errors in AC Bridges

    Homework Statement I m not able to understand one of the methods to reduce error in measurement using ac bridges. "All the leads to a single corner should be brought as nearly as possible to the same point" Homework Equations I am providing the bridge layout image and a,b,c,d are corners of...
  16. D

    AC Bridge: Solve Unknown Inductance/Resistance

    Homework Statement I have given the T - bridged network figure and I have to calculate unknown inductance and resistance? Homework Equations I solved a lot of bridge problems using balanced bridge equation :- (Z1)(Z4) = (Z2)(Z3) But I have no idea how to proceed in this question , please...
  17. K

    Switching research groups without burning bridges?

    I'm currently a third year undergraduate doing semiconductor research for about one semester and a summer and I absolutely hate it! My professor doesn't have that many grad students and his lab is severely under funded. I don't have my own mentor/grad student and I've been blindly doing a...
  18. L

    What is the mass of the counterweight in a two-leaf bascule bridge?

    Modern day draw bridges are also known as bascule bridges. These can have one or two sides (one is called a leaf) that are drawn up from each end of the bridge so that boats can pass through water channels. In some designs, each side of the bascule bridge is held in place by a counter-weight...
  19. S

    Which would be strongest (popsicle stick bridges)?

    In a popsicle stick bridge, would it be stronger to have the sides be in the form of a triangle, or a sort of uneven arch. I can cut the popsicle sticks to help make an arch (or use full ones), but it'll be difficult, and probably won't be done so well. It might just be better to stick with a...
  20. R

    Measuring Parabolas of a Suspension Bridge - Alex

    I was given the assignment to measure the parabolas of a suspension bridge. I have some ideas for how to go about it, like using a point of reference and going out from there. I was wondering if anyone had any other ideas. Thanks! Alex
  21. A

    Is Normal Reaction Higher on Concave Bridges Than Convex Bridges?

    I want to know when a vehicle travels at a constant velocity along a convex and concave bridges, in what bridge the normal reaction of the vehicle is higher... I think it is on cancave bridge... am I right? because I got it by equations...
  22. Monocerotis

    Can the Seven Bridges of Koenigsberg Problem Be Solved with Modern Technology?

    Was Euler's solution that there is no solution to the problem ?
  23. T

    What exactly are North and South bridges?

    What exactly are "North and South bridges?" I was hoping to upgrade my motherboard this Christmas. I know I need an LGA 775 socket, and I also know that even though a motherboard may have the same socket type as your CPU requires, the bridge types may be different, making it completely...
  24. R

    Breaking Light and Einstein-Rosen Bridges?

    Quick question I don't expect many replies to, but I'm just wondering: Could exceeding the speed of light (if it were possible) be described as creating an Einstein-Rosen Bridge because of the accelerating object's relativistic mass? Yes? No? And if so, would it have any strange properties...
  25. O

    Interesting lesson on Wheatstone bridges

    I enjoy learning new things every time I do a problem set. Take the wheatstone bridge for example. Upon my initial observation, I concluded that the total upper electric potential(V1 + V2) minus the lower electric potential(V3 + V4) ought to give the electric potential that exists across the...
  26. F

    Did I just torched some bridges?

    So today, I told my advisor that I needed to submit a plan of study by the end of this semester. Originally I was suppose to go the thesis route, but I decided to just take the safe route and take the extra courses to graduate instead of possibly extending my graduation and failing the defense...
  27. J

    Why are arch bridges stronger than beam ones?

    When building a pasta bridge, why are arches or triangular peaks able to support more weight than flat beam bridges? Assume the weight would be attached to the base/deck of the bridge. I'm building a pasta bridge for my Physics class and I was curious. Thank you!
  28. T

    Optimizing Salt Bridge Conductivity in Voltaic Cells

    Iam doing an experiment on voltaic cells in particular Iam studying the effect that the thickness of the salt bridge has on the emf of the cell over time. iam thinking that the thicker the salt bridge the longer it will last. I think that will happen because maybe there is more surface area...
  29. E

    Suspension Bridges: What is the Shape Called?

    What is the name for the shape that the suspensions on a suspension bridge make? I think it is something like canary?
  30. Loren Booda

    Plastic Bridges: Practicality and Feasibility for Bridge Construction

    Is there any practicability for making bridges out of plastic?
  31. E

    Comparing Bridge Forces: With & Without Trusses

    I'm doing a research paper on bridges, and I'm having trouble finding an example contrasting the magnitudes of forces on a bridge with trusses as opposed to a bridge without trusses. I understand pretty clearly how a truss works, however I need to give an example with numbers, and I'm not...
  32. tandoorichicken

    Wheatstone Bridges: Which Has Greater Static Sensitivity?

    Say I have two Wheatstone bridge circuits: On each of them, the top half of the diamond is formed using two fixed resistors. The bottom half of each diamond consists of a variable resistor on the left and a resistance temperature detector on the right. Now, for the first bridge circuit, the two...
  33. S

    Conflict bridges of graph, where it from

    I've been taught in lecture last week about graph planarity testing. But the main idea of conflict bridges I still don't understand. Then I search online, from wikipedia to mathworld, there are nothing about this bridge concept. I begin to wonder if this idea is a standard method to do this kind...
  34. E

    Help Me Understand: Why Do Soldiers Out of Step on Bridges?

    hi my math teacher ask us this the other day..."in the military, as marching soldiers approach a bridge, the command route step is given. the soldiers then walk out of step with each other as they cross the bridge. explain." i don't understand what she means at all. is it even a physics concept...
  35. J

    Bridges and Archimedes' principle

    I was reading some of my physics chapter and cam across an interesting question, which I am sure someon here can answer. It just interested me, so here it is. A barge filled high with sand approaches a low bridge over the river and cannot quite pass under it. Should sand be added to, or...
  36. S

    Triangles, Bridges And Centripetal Space Habitats

    Making metal bridges from steel triangles is a very good idea because triangles are one of the strongest known shapes. My question is, would making a bicycle wheel-like space station's foundation braced with lots of triangles of whatever construction material is used(carbon fiber, aluminum...
  37. S

    The Seven Bridges Of Konigsberg

    Hello Everyone, I was trying to solve couple of fun problems. Many of you must have heard about the famous The Seven Bridges Of Konigsberg and how Euler solved the puzzle. You can do a quick google... Here is a diagram if you want it... http://www.contracosta.cc.ca.us/math/BridgeGraph.GIF...
  38. I

    Anyone good with wood and bridges?

    Hi everyone! I haven't been here in a while, and I see there've been a lot of changes. The place looks as groovy as ever. :smile: I have just been assigned a bridge builiding project. We're supposed to make the bridge out of only wood that ways 25 grams or less and be able to...
  39. H

    Crossing Bridges: Take Our Survey!

    bridges anyone? We're doing a project for my engineering tech class, and i need to conduct a survey, we'd be really obliged if u could answer the survey questions. 1. When thinking about bridges, what is the first bridge that to your mind? 2. Why? 3. If crossing a bridge, do you look over...
  40. O

    Why do bridges have weight limits?

    You've probably seen pictures of bridges carrying rush-hour traffic, so obviously the bridges are designed to bear enormous weight. Yet, they have weight limits on trucks. Imagine - a truck hauling only maybe 1/50 of the total mass of the rush-hour traffic is supposed to be dangerous to the...
  41. D

    Earthquake bridges and towers (new)

    Bridge to 7 km and towers to 3.5 km. (plus other lightweight designs) at: http://groups.msn.com/DavesBridgesandTowers My last thread was just starting to get interesting when the new forum took over! For anyone who missed the final messages, I have recently added more drawings to the site...