# How do you make a box girder?

## How do you make a box girder?

One of the most commonly used forms of superstructure in concrete bridges is precast girders with cast-in-situ slab. This type of superstructure is generally used for spans between 20 to 40 m….Analysis and design of prestressed concrete box girder bridge.

Eccentricity (mm) | Prestressing Force (kN) | The eccentricity which give minimum prestressing force (e) = 731mm |
---|---|---|

731 | 16489.15 |

**What is the purpose of a box girder?**

Box girders are used for the construction of a cable-supported bridge, curved bridge, and footbridges. It is rarely used in buildings, but they may be used in special circumstances, such as when loads are carried eccentrically to the beam axis.

### What is a steel box girder?

A box girder bridge is one in which the principal structural element is one or more closed cells, acting in bending. Box girders are used for highway bridges, railway bridges and footbridges – different structural forms are chosen for each of these applications.

**What is prestressed box girder?**

Prestressed concrete (PSC) box girders are concrete sections forming a boxed shape (rectangular or trapezoidal) supported by prestressed strands. These girders are widely used for footbridges, highway bridges, and railway bridges.

#### What type of bridge is the box girder?

A box girder bridge, or box section bridge, is a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises prestressed concrete, structural steel, or a composite of steel and reinforced concrete.

**Why a box girder bridge is made hollow?**

use in bridge construction The hollow box gave the deck the extra stiffness of a truss, but it was easier to build and required less engineering precision—at the cost, however, of extra material.

## Why is steel used for box girders?

Improved durability; reduced maintenance of protective coatings since the exposed surface is less and fewer edges are there and avoidance of exposed horizontal surfaces, no exposed bracing and stiffeners; Clean lines of a closed box girder provide better appearance for footbridges where the visual impact counts.

**How do you calculate girders?**

The formula for solving the required number of pieces of plywood for formworks of girders is P = 2 ( d ) + b + 0.10. ‘P’ is the perimeter of the three sides you want to estimate, ‘d’ is the length of the vertical side and ‘b’ is the bottom form.

### How do you find the volume of a girder of concrete?

Calculating the top surface area and multiplying it with the depth or height of the column.

- Volume of Concrete = 0.6×0.4×3= 0.72m3
- Volume of Circular column = πr2 x 3 = 3.14 x 0.252 x3 = 0.58m3
- Volume of concrete = 1.2x1x0.1 = 0.12m3 Total volume of concrete required for footing= 0.32+0.12=0.44m3

**What are the methods to design girder?**

Girder Design Procedure:

- Calculate the bending moment to be opposed by the beam with respect to loads and span of the beam. Let the maximum bending moment to be opposed is M, and maximum shear force is F.
- Calculate the suitable measure of modulus of section by the below given formula.
- Select a rolled steel section.

#### What is the purpose of the box girder?

Box girders are utilized for the creation of a curved bridge, cable supported bridge , as well as footbridges . Moreover, it is not often utilized in structures, although they could be utilized in particular conditions, for instance at the time that loads are transported off-center/eccentrically toward the beam axis.

**What are the disadvantages of box girder bridge?**

On the other hand, box girders are more expensive to fabricate, and they are more difficult to maintain, because of the need for access to a confined space inside the box. Corrosion of the steel cables that provide the post-tensioning for box girder bridges has become a major concern.

## What is a box girder bridge, anyway?

A box girder (also known as a tubular girder) is a bridge in which the main beams comprise girders in the shape of a hollow box. The box girder normally comprises either prestressed concrete, structural steel, or a composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in cross-section.

**Are steel girders different from steel beams?**

The major difference between steel beams and steel girders is the size. Usually, large beams are known as girders. If a large beam horizontally supports a structure then it is a steel girder. Structural steel fabricators make different types of beams depending on its length, width, and weight. Beams are usually smaller in size compared to girders.