Structural Sustainability Analysis of Pratt Truss Bridges

Introduction

A truss bridge is a type of bridge thats main element is a truss, meaning of the word truss is a structure of connected elements that form triangular units. Truss is used because it is a very inflexible within the structure and it is a transfer of the load from a single point to a much wider area. Truss bridges appeared very early within the historical fields of modern bridges and are economic to construct because they use materials efficiently.

The importance within the use of truss is that this specific part of a bridge is exceedingly important and essential because it allows the truss bridges to withstand compression forces with squeezing together, like when a heavy car drives across and tension forces stretching apart, like when extreme weather takes place.

The Reason for researching this topic specifically is due to my field of passion and future study within the fields of architectural engineering. The advantages within using this method which is the truss bridge method is that the wood trusses can be used to span distance of up to 35 meters, that is more than enough and essential for the creation of very durable and long-lasting bridges with a good base and format so that the bridge will be stable throughout a long period of time.

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Truss enables the creation of light structures that can span large distances and endure very heavy loads. This is important so that the readers know the essentials need within the sustainability of a bridge.

The importance of the position of the bridges placement within it force and angles.

Methodology

The structural integrity of a Pratt truss bridge relies on its ability to withstand compression and tension forces. The study involves calculating these forces within the truss system and determining the optimal angles for the truss elements to ensure the bridge's sustainability.

Calculations

Step 1: Force Balance Calculation

To ensure equilibrium, the sum of moments around a point (denoted as EMa) is set to zero. Considering the forces acting on the bridge and their distances from a pivot point, we calculate the force supported by the bridge's base (Fb).

EMa = 0

Clockwise direction =(-);

-(6KN)(2m) - (6KN)(4m) - (6KN)(6m) + Fb (8m)

When brought to the other side the (-) converts to (+)

Fb = 72 KN/m divided by 8m = 9KN.

9KN are put in both sides due to the bridge being symmetrical

In this calculations we have calculated the angle of the pressure and force.

Step 2: Compression and Tension in the Truss

Using the determined base force, we calculate the compression and tension in different sections of the truss.

9KN/4 = HB/5 = EB/2

This calculation is to calculate the compression within the portion taken in the truss bridge diagram:

HB/5 = 9 KN/m → cross multiplication

HB = 9KN(5m)/4 = 11.25 KN

This calculation is to calculate the tension within the portion taken in the truss bridge diagram:

EB/2 = 9 KN/4 → cross multiplication

EB = 9 KN( 2m)/4= 4.5 KN

Step 3: Calculating Forces in Diagonal Members

The forces in diagonal members DH and DF are calculated considering the symmetry of the bridge.

DH/5 = 3KN/4 → cross multiplication

DH = 3KN(5)/4 = 3.75 KN

DF/5 = 3KN/4 → cross multiplication

DF = 3KN(5)/4 = 3.75 KN

When calculated both had accurately gotten the same answer due to the true drudge being symmetrical

GH = (11.25)(cos 53.13 degrees) + 3.75 KN (cos 53.13 degrees)

= ( 15 KN)(cos 53.13 degree)

= (15 KN)(0.6)

= 9KN

Conclusion

The sustainability of a Pratt truss bridge hinges on meticulous calculations of forces and angles within its structure. Through the analytical process outlined, we've demonstrated the bridge's capability to withstand significant compression and tension forces. The Pratt truss bridge's design efficiently distributes loads across its structure, making it a viable and sustainable option for spanning large distances. The structural analysis underscores the critical role of precision in engineering calculations to ensure the longevity and safety of bridge constructions.

Future Implications

The findings from this study emphasize the importance of continuous innovation in truss bridge design and the integration of advanced materials to further enhance sustainability. As architectural engineering progresses, the principles laid out in the analysis of Pratt truss bridges will continue to serve as a foundation for developing more resilient and efficient bridge structures.