DISEÑO Y ANALISIS BASICO DE LA CERCHA Y ARCO DE UN PUENTE VEHICULAR

DISEÑO Y ANALISIS  BASICO DE LA CERCHA Y ARCO DE UN PUENTE VEHICULAR

Ordoñez J., Revelo J., Obando K., Marcillo A.

Universidad Mariana, Facultad de Ingeniería, Ingeniería Civil

RESUMEN:        

The project established the design of an arched bridge for vehicular traffic in the city of Sapuyes Nariño, with which it is intended to improve road infrastructure in the municipality, allowing further development and improve communication with the surrounding areas. The design was based on projects where arch bridges were implemented, the AutoCAD graphic software was used to generate the design level; the dimensions were taken and the structure of the arch and truss that supports the board, to analyze the knowledge acquired in comprehensive physical and mechanical calculation is implemented, so that the arc length is determined analyzed, as well as the area to be generated under the curve, the nodes method used to calculate the forces exerted by the board on the trusses that support it..

1. INTRODUCCION:

The bridge is a structure that saves an obstacle, whether river, ditch, ravine or via natural or artificial media, and to allow the passage of pedestrians, animals or vehicles. All bridges are based on natural models, which, as technology has progressed, we have incorporated new ways of solving the same problems. From a tree toppled onto a bed, a detached stone hillside or a tangle of lianas and vines stretched over a ravine, which have always served to save natural features, has mounted a science that is important part of the application civil engineering^[1].

The bridge is chosen for the project arch bridge, which is characterized by

Having supports located at the ends of the light to save, among which a structure is provided with an arc with which loads are transmitted. The board can be supported or hung from the main structure, giving rise to different types of arch bridge according to the board position relative to the arc.^[2].

The arch bridges work by transferring the weight of the bridge and live load to the support by compressing the bow, where they transform into a horizontal thrust and vertical load^[3].

Given the many segments that make and stabilize the arch bridge, the importance of physical and mathematical analysis of these structures are highlighted as they are routed to establish the characteristics and physical and mechanical properties that interact in the structure, and allows stability, design and long-term sustainability.

1. APPLICATIONS FOR AUTOCAD

AutoCAD drawing program was used to develop the plan and project design; the design was based on different projects which were implemented arch bridges; in Figure 1, 2 and 3, we can see the design proposed for the project bridge.

Fig. 1 isometric arch bridge view

Fig. 2 Arch bridge front view[pic 1]

[pic 2]

Fig. 3 Arched bridge top view

[pic 3]

The finished design necessary for project analysis dimensions were taken.

1. CALCULATION APPLICATIONS

Based on the plane dimensions are taken for calculations.

Fig 4 bridge scheme for the analysis of calculation

[pic 4]

1. Area Under the curve.

We describe the formula for the area of the bridge:            

       [pic 5]

According to the arc of the bridge we can describe the equation as:

[pic 6]

a = Space that forms the arch of the bridge.

To calculate the area under the curve, we propose the following integral:

[pic 7]

[pic 8]

[pic 9]

            [pic 10]

[pic 11]

[pic 12]

[pic 13]

The area under the curve is of great importance to determine the light that the bridge will thus be implemented to gauge the effects of the river that saves, since

the riverbed can generate wear as undercuts in the structure.

1. Arc Length

For the arc length we plant the following integral, based on the equation describing the arc equation

[pic 14]

[pic 15]

[pic 16]

               [pic 17][pic 18]

           = [pic 19][pic 20]

           = [pic 21][pic 22]

[pic 23]

= [pic 24][pic 25]

= [pic 26][pic 27]

=[pic 28]

=19,15m

The arc length becomes important when calculating budgets as when dimensioning the structure will have a base number of materials can be used at the time of construction.

1.  volume calculation.

In order to calculate the volume of the bridge deck we will begin by defining the dimensions Figure 5

Fig 5 Scheme of the bridge deck

[pic 29]

Where: X=24 m; Y=0.50m; Z=0.50 m

The volume equation is defined:      

                               [pic 30]

[pic 31]

[pic 32]

The calculation of the volume was useful to calculate the volume of the board and thus determine their weight by calculating the density of the materials that comprise it.

3.4 Rate Variation

We cylinders forming bridge railings, height (h) figure.6 constant, with which variation the area of the cylinder with respect to the variation of its radius was calculated.  

Fig 6. Segment of the railing of the bridge[pic 33]

[pic 34]

Where: π = 3.14

              h = 1m

              r = 0.05m

Therefore it represents the change as follows:

[pic 35][pic 36]

                                            [pic 37][pic 38][pic 39]

With the calculation of the variation can determine the area occupied railings on the bridge, which is very important for sizing the board since it must ensure adequate space for vehicular traffic; and it is also important to determine the cost of different materials that can be developed.

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