Technology I Bridge Building

Introduction In this bridge building activity you will start with learning the different aspects of bridge construction and eventually construct your own bridge that will be tested. Following this introduction you are expected to take all note needed to help you through this activity. In this activity you will learn the basic process of problem solving and the process of design. You will do this by designing and constructing a bridge of your own that will be tested for efficiency.

Static and Dynamic Loads Static loads – are those associated with a load at rest Dynamic loads – are characterized by forces in motion

Forces Internal Forces – are generated by the molecular structure of the material in question to counter external forces External Forces – are the loads that are applied to the object in question

Forces Equilibrium – is when forces are equal

There are 5 different ways forces can be exerted on a structure Compression Tension Bending Shearing Torsion

Compression Compression – when the load is applied to the top of a structure. The load is pressing down on one end of the element and the ground is pressing up on the other end. Compression loads try to collapse the element.

Tension Tension – A load is applied along the element in a pulling action. Tension forces try to pull the element apart.

Bending Bending – Bending forces cause the material to be under both compression and tension

Shearing Shearing – When forces are exerted on a material in the same plane but in opposite directions. This causes one section of a board to slide past adjacent board material. Scissors use shear force to separate material.

Torsion Torsion – In application such as a drive shaft. Torsion describes forces that try to twist the material apart.

Stress and Strain Stress – The strength of a material is described by its stress. It is the force being exerted on the molecules of a material by compression or tension force. Strain – is used to describe the change in shape of a material caused by compression or tension forces. How far the material stretches under a load.

Parts of a bridge Super Structure – The structure above the roadbed that helps distribute the load. Truss – Pre assembled triangular frame used in the super structure. Sub-Structure – Is part of the bridge that rests on the foundation. This is located below the roadbed. Abutments – The supports at the ends of a bridge that support the bridge itself as well as the earth at the ends of the bridge.

Parts of a bridge continued Piers – The vertical structural supports. They help keep the bridge from sagging. Piles – When the earth is not stable and can not support a load, piles are placed to help strengthen the foundation. Slab – (road bed)

Types of bridges

Types of bridges continued

Types of bridges continued

Types of bridges continued

Types of bridges continued

Types of bridges continued