What is Bridge: Definition and 481 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. Z

    Bridge between complex analysis and differential geometry

    I am not a mathematician but I have noticed how strangley similar the treatments of curvature and residues are when you compare the residues of residue calculus and the curviture of the gauss bonet forumlation of surfaces. Is there some generalization of things that contains both of these...
  2. P

    Einstein podolsky rosen bridge

    hello where can i found study books about einstein podolsky rosen bridge ? can i get names of books that explain the theory of einstein podolsky rosen and worm hole thanks.
  3. matthyaouw

    What are these thingies on suspension bridge cables?

    Since I know there are a lot of engineer-types in these parts, maybe someone knows what these things are. Ther's a thing clamped high up on to the cable on the right, and every other cable on the bridge but I can't for the life of me work out what they are there for. any insight?
  4. Saladsamurai

    Wheatstone Bridge Strain Gauge Question

    Homework Statement I recently did a bending lab with a WB Strain Gauge in a bunch of different configurations. One measurement in particular is bothering me. Referring to the figure below, there are four strain gauges, Yellow, Orange, Black and Red mounted to a cantilevered beam with an...
  5. K

    Building a cardboard bridge

    I am building a cardboard bridge that is supposed to span 7-9 feet and made of cardboard. I am having trouble however designing the abutments. The bridge will simply be placed on a table (no suspension designs btw) and will have a maximum 10% grade. What will be the best way to design the...
  6. T

    Building a bridge from Alaska and Russia?

    I think I saw a documentary on TV a while back about the thought of building a bridge between Alaska and Russia. The largest bridge ever built. Do you think that this could actually be done in terms of modern structural engineering? I would imagine that such a bridge would become quite a...
  7. V

    Minimum microstrains that a wheatstone bridge or strain gauges will pick up?

    I'm wanting to measure the torque output of a cyclist by measuring the shear force induced in the crank arms. I've done some calculations for the minimum amount of strain that I'll want to pick up and it is around 6e-6 m/m. I'll be using a full wheatstone bridge with a constant voltage...
  8. Gordy

    Bridge Aerodynamics Project Ideas

    I am in sort of a critical bind: I've been working for several months on an ISEF entry as part of a class (actually, working on the project IS the class), and in the past week it has completely fallen apart -- I won't go into details, but there is absolutely nowhere I can take the project...
  9. S

    What exactly is a wheatstone bridge? What are its uses?

    I would like to know what is a wheatstone bridge? I read that it is an arrangement of resistors but i am not understanding how it works and the whole concept. Any help would be appreciated. Thank You.
  10. O

    Forces surrounding Car on a Bridge

    Homework Statement An W = 7500 N automobile is stalled one-quarter of the way across a bridge (see Fig. P77). Compute the additional reaction forces at supports A and B due to the presence of the car. Take the length of the bridge to be AB. Homework Equations The Attempt at a...
  11. E

    How to calculate tension/compression in a truss bridge (diagram shown)?

    In general, in a truss diagram the forces like load, reaction force are act on joints but in this case the load is in the middle of two joints. How can I find forces on members in this case? Your help is really appreciated. Thank you for reading
  12. S

    Building a Bridge with Balsa Wood

    I need to make a bridge using Balsa Wood, but I can't decide whether to use the Howe or Pratt Truss. Requirements maximum mass of 25 grams maximum test load will be 15kg must allow a 5.0 (∼2”) cm cube to pass along the roadway without touching the structure must be an opening at the...
  13. A

    Exploring the Tacoma Narrows Bridge Collapse

    Homework Statement Hi, i want to do a science fair project on the Tacoma Narrows Bridge Collapse. I want to do a research on the Tacoma Narrows Bridge collapse and how it taught us what structures stabilize a bridge against wind forces. I also want to build something that would demonstrate the...
  14. L

    Natural angular frequency of a bridge

    1. Consider an oscillating system of mass m and natural angular frequency omega_n. When the system is subjected to a periodic external (driving) force, whose maximum value is F_max and angular frequency is omega_d, the amplitude of the driven oscillations is A=\frac{F_{\rm...
  15. A

    Building an H Bridge 8A Circuit on a Bread Board

    Hello forum , i want to ask you a simple question , i am building a circuit on a bread board, the circuit is an H bridge 8A , is normal bread board can handle this current or the connection inside the bread board will be in not safe mode ? Thanks for reply, Have a nice day
  16. I

    Solve for Person's Final Height After Jumping Off Bridge

    Homework Statement Mass of person jumping off bridge = 60 kg The bridge is 60m above the river The cord only starts stretching after he falls 20m. k = 50 N/m Homework Equations gravitational potential energy = mgh elastic potential energy = (1/2)kx^2 The Attempt at a Solution...
  17. S

    Bridge circuit - 5 eqns with 5 unknowns

    Homework Statement The bridge circuit for this problem: http://img52.imageshack.us/img52/7366/bridgecircuit.jpg I have to derive a formula for the equivalent resistance (Req) of the bridge circuit shown in the link.Homework Equations I've been able to come up with the 5 equations with 5...
  18. E

    Arch Truss Bridge, Static Determinacy

    Homework Statement This is for a bridge design project. We went for an arch bridge over the roughly parabolic valley. The arch is parabolic and rises 1.3 meters above the deck of the bridge. The deck is divided in 20 sections and supported by both vertical and diagonal members (hollow...
  19. T

    Wheatstone bridge to measure high resistances?

    Can a wheatstone bridge be used to measure very high resitances with good accuracy? If not what problems interfere?
  20. W

    Maximum speed of a car on the bridge

    the vertical cross section of a bridge is a circular arc of radius 300 m. what is the maximum speed at which the car will not leave the surface while passing at the top of the bridge? i just can't seem to understand where to go with this problem help please!
  21. A

    Bridge rectifier and symmetric power supply

    Could some one explain how a bridge rectifier works with a diagram and its mathematics? Also please explain how a center tap transformer and a bridge rectifier are used to provide a symmetric power supply. I have the Ckt Diagram for that but I cannot understand its working. thanks...
  22. A

    Load Distribution of an Arch Bridge

    Ive made a spaghetti bridge for my grade 9 science class and I was wondering if anyone could help me find out how a static vertical load from the center my spaghetti bridge would be distributed along my structure to the edges. It is made entirely out of spahetti and hot glue and is designed to...
  23. J

    Where is the bridge between Calculus and Physics?

    I am soooo lost. I don't even know if this is the right forum. But where is the bridge between Calculus and Physics? I can Integrate equations, but when it comes to physics, i for one, don't know when to integrate; two, i don't see how you find the constants to remove from the integral; and...
  24. N

    Cable to be used for the suspension bridge

    Homework Statement The cable to be used for the suspension bridge can safely support a tension of 40 MN.  Calculate the shortest length of the cable that can be used to construct the bridge.  Calculate the corresponding value of h. (Neglect the issue of safety factor). L = 72...
  25. T

    Can toothpicks and wood glue mimic real bridge designs for a school project?

    I have a question about bridges. I am not sure if this is the right place, since everyone else is discussing more advanced things, but I couldn't find anything (I did try to search). If this post is out of place just please redirect me. For school I need to design and then build a bridge to...
  26. C

    Engineering Converting Wheatstone Bridge: Possible or Not?

    In the attachment below, I have a picture of both an original wheatstone bridge and my attempt at converting it to a more familiar looking circuit. Is what I did correct/even possible? I just want to get a better understanding of these types of circuits. Thank you for your time!
  27. T

    Statics Problem - Moment on a Bridge

    Homework Statement The uniform work platform, which has a mass per unit length of 28kg/m, is simply supported by cross rods A and B the 90-kg construction worker starts from point B and walks to the right. At what location S will the combined moment of the weights of the man and platform...
  28. A

    The old man and the bridge

    An old man has built his beautiful house on an unused bridge for excellent scenic views of the landscape. However there is a problem, demolition crew has arrived and have set charges to the sides of the bridge that connect it to the land-masses. The demolition crew does not know of the old man...
  29. W

    Game of Bridge: Easily Finish Dealing Cards After Interruption

    You're playing a game of bridge with 4 people. You're dealing the cards, when suddenly the phone rings and you go pick it up. When you come back to the table, you can't remember who got the last card. How do you finish dealing the cards quickly and without counting the cards of any player, with...
  30. Z

    Balance condition for inductor bridge

    1. A Wheat stone bridge resembling setup is given with two parallel branches , the 1st containing an Inductor of Inductance L1 and resistance R1 in series with a resistor R2. The second branch consists of inductor with inductance L2 and resistance R3 in series with a resistor R4. The branches...
  31. S

    No load output voltage of a bridge rectifier

    Will a bridge rectifier circuit without a filter or load resistor connected across its output deliver a pulsating unidirectional voltage ? An oscilloscope trace (dc input enabled) did show a trace of a full wave output though the half sine did not swing down to zero voltage completely and...
  32. P

    Full-Wave Bridge Rectifier Filter + Regulator DC Power supply

    http://img104.imageshack.us/img104/3557/1234uyq.jpg Ok, there are a few calculations on this problem that I am having difficulty with. This is a past homework assignment which is why the answers are filled in. They are all correct. Anyways I approached the problem in this manner: V...
  33. A

    Solving Diode Bridge Current with AC-to-DC Circuit

    Hello, I made a circuit to convert AC to DC. It looks like this. http://openbookproject.net/electricCircuits/Semi/03267.png My output DC voltage is around 5 volts. Could someone please explain to me how I could figure out the current running through each of the phases at a given time given a...
  34. B

    Weight of barge on a bridge canal/acqueduct

    Homework Statement In England in the Middle Ages an extensive system of canals was used for transportation. Some of these canals crossed over canyons by flowing over bridges (viaducts). Suppose that a heavily loaded barge crossed over such a waterway bridge. A)The force on the bridge would...
  35. O

    Understanding the Wien Bridge Oscillator Circuit

    Hi all, I am doing a project on electronics about the Wien Bridge Oscillator. I learned about impedances and operational amplifiers and now I'm trying to understand the Wien Bridge circuit. I'm having some problems understanding it and I would be very happy to get some help. I still have not...
  36. W

    Linear Thermal Expansion: Bridge Joints

    SOLVED Homework Statement A bridge is made with segments of concrete 80 m long (at the original temperature). If the linear expansion coefficient is 1.2 x 10^-5 (1/degrees C), how much spacing is needed to allow for expansion for an increase in temperature of 50 degrees F? Answer in units of...
  37. O

    A beginning RC circuit that resembles a wheatstone bridge

    Everybody knows what a wheatstone bridge looks like. R1 and R2 are on top and R3 and R4 are on bottom and R5 is in the middle of the angled box shape. let's replace R1 and R2 with 2 different capacitors. Let's also replace R5 with a switch. How would you figure out the potential...
  38. P

    Chinese bridge jumper gets push from passer-by.

    http://news.bbc.co.uk/2/hi/asia-pacific/8064867.stm If you were a Chinese official in a position of authority, what would you have done regarding Mr Lai's actions? How would you have treated the situation? Basically, would you have had him arrested and charged or would you secretly (or...
  39. V

    Constructing a Strong Bridge with Limited Materials

    Hello! In my geometry class we are going to be making a bridge. The materials are: 15 3mm x 3mm x 683mm balsa wood glue cutters Arch bridges are to difficult for our materials and we can't make a suspension bridge because we have no string. What is the strongest bridge I can make...
  40. M

    Bridge and center-trapped full wave rectifiers

    Homework Statement Why the output DC voltage of the center trapped rectifier is half that of a bridge rectifier??
  41. O

    Calculating Wheatstone Bridge with R1=600, R2=R3=R4=400, V Supply=10V

    if r1 has value of 600 and r2=r3=r4=400 ohms. supply voltage is 10v. im getting the wrong answer and do not know how. im using [(R4R2 - R3R1) / (R1+R4)(R2+R3)] * VS i get an answer of [160000 - 240000 / (1000)(800)] * 10 = [-80000 / 80000] * 10 = -1ohm but this is the incorrect answer...
  42. O

    Straw Bridge Building Project Help

    Currently I am doing a straw building project with a group and we are in need of an interview from a real life engineer. So if anyone can help me with my design on our Girder Bridge then it would be appreciated.
  43. L

    Influence the overall strength of a truss bridge?

    Hi all, I've been looking at a few trusses lately and was wondering what the main factors are that influence the overall strength of a truss bridge? I have an idea that the more members taking loads, the stronger the truss, hence members should be at sharper angles. Of course i could be dead...
  44. C

    Understanding Half Bridge Strain Values

    Hi, I am using a half bridge strain gage configuration on a simply supported beam. If i get negative strain, does that mean I am getting a positive force or a negative force on the beam? I am confused since one gage is in tension and the other is in compression. Thanks
  45. G

    Bridge Circuit (resistors, whoo)

    Homework Statement The resistor R in the above figure has a resistance of 21.7 Ω. a) Find the current in the resistor R. (Enter a positive number for a current up and to the right, and negative for down and to the left. b) Find the current in the 10-Ω resistor. (Enter a positive number for a...
  46. C

    About Wheatstone Bridge Method

    I need your help to finish my homework.I have only two questions 1-If a diameter of a wire is doubled,what happens to its electicial resistivity? 2-Why is different the resistivity of materials? Thanks
  47. X

    R1 350 Ohms: What Current Flows at 50V?

    Homework Statement What current flows through resistor R1 (350 Ohms) in the figure when the applied voltage is 50 V? Homework Equations V = IR ? The Attempt at a Solution I would have thought the answer would be zero because I thought the potential at R1 is equal (but this was incorrect)...
  48. B

    Build a Strong Balsa Wood Bridge: Tips, Tricks, and Requirements

    Hi, I am not sure if this belongs here and I apologize in advance if this has been placed incorrectly. Please move it to the appropriate forum. I have a Balsa bridge due in about 2 weeks. I have picked up the supplies but I am not sure how to start the process and I want to do it...
  49. T

    Electrochemistry (batteries), Wheatstone bridge question.

    Hi, I am using a Wheatstone bridge to measure very low resistances (around 0,2ohms) and my measurements are changing from day to day. If I take the resistance measurement of the same resistor several times, I notice that each measurement will be lower than the next. But the next day, the...
  50. E

    Current Sensing Resistors in an H Bridge Circuit

    I am using the UC3638 PWM chip to drive a motor. I was wondering if the current sensing resistors are required, and if someone could translate how they work? How are they used for peak current limit control and in their absence what happens? If more information is needed, its powered from a...
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