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You should understand from these demonstrations that the geometry of the stable, hinged |
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triangle structure allows several essential things to happen. The external forces and |
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internal reactions are intimately linked. That is, increasing the external forces directly |
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increases the internal reactions. Also the internal compressive and tensile stresses induced |
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by the external load and the internal compressive and tensile reactive forces exerted by |
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the structure's material are in direct opposition to each other. As a consequence these |
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internal induced and reactive forces are aligned axially, that is, parallel to each other along |
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the longitudinal axis of the members. It is these properties that cause the hinged triangle |
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structure to be stable since they enable the external and internal forces to be balanced. |
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. |
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Now that you have a basic understanding of what makes structures stable and how external |
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loads cause structural members to experience compressive and tensile stresses; let's see |
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how these factors affect the design and performance of real structures like columns, beams, |
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bridges, buildings, spaceframes, and towers. |
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Columns and beams of some form are the fundamental building blocks of most man-made |
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structures. They are complimentary structural elements that function together to enclose |
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space or support a framework. Columns (colored green above) are upright members whose |
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function is to support an elevated framework and transfer its loads to the ground. They are |
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subjected to compressive stresses mainly since they are being squeezed between the load |
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bearing down on the top of the column and the ground pushing back on the base of the |
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column. Beams (colored yellow above) are horizontal members that span between columns |
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or walls. Their function is to collect the load of the elevated framework of which they are a |
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part and transfer it to the tops of the columns or walls. They are subjected to bending |
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induced stresses of tension and compression mainly since they are supported on their ends |
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by columns or walls and loaded in the middle by the weight of the elevated framework. |
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Back to Knowhere |
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