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BEAMS MOMENT OF INERTIA
The formula for the moment of inertia I=∫(y^2)da reveals that the resistance of any differential area da increases with its distance y from the neutral axis squared, forming a parabolic distribution....
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BEAMS SHEAR STRESS
The distribution of shear stress over the cross-section of beams is derived, referring to a beam part of length x marked on diagrams. Even though horizontal and vertical shear are equal at any part of...
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SHEAR STRESS IN WOOD AND STEEL BEAMS
Based on the forgoing general derivation of shear stress, the formulas for shear stress in rectangular wood beams and flanged steel beams is derived here. The maximum stress in those beams is...
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SHEAR STRESS IN WOOD I-BEAM
Since this is not a rectangular beam, shear stress must be computed by the general shear formula. The maximum shear stress at the neutral axis as well as shear stress at the intersection between...
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SHEAR STRESS IN STEEL BEAM
This beam, supporting a column point load of 96 k over a door, is a composite beam consisting of a wide-flange base beam with 8x½ in plates welded to top and bottom flanges. The beam is analyzed with...
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TYPICAL BEAM DIAGRAMS
Deflection, shear, and bending diagrams are shown here for typical beams. The beam with deflection and load diagrams are drawn on top with shear and bending diagrams shown below. With experience,...
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Wind Load - Structural Design
1 Wind load on gabled building 2 Wind load on dome or vault 3 Protected buildings inside a city 4 Exposed tall building inside a city 5 Wind flow around and above exposed building 6 Wind speed...
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Wind effect - Structural Design
A building in the path of wind causes wind pressure which in turn causes force, shear, and overturn moment at each level that must be resisted, following a load path to the foundations (wind wall...
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Seismic Design
Earthquakes are caused primarily by release of shear stress in seismic faults, such as the San Andreas fault, that separates the Pacific plate from the North American plate, two of the plates that make...
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Structures - Design Response Spectrum
The IBC Design Response Spectrum correlate time period T and Spectral Acceleration, defining three zones. Two critical zones are: T < TS governs low-rise structures of short periods T...
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Structures - Horizontal Floor and Roof Diaphragms
Horizontal floor and roof diaphragms transfer lateral load to walls and other supporting elements. The amount each wall assumes depends if diaphragms are flexible or rigid. 1. Flexible...
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Seismic Design, Eccentricity
Offset between center of mass and center of resistance causes eccentricity which causes torsion under seismic load. The plans at left identify concentric and eccentric conditions:1 X-direction...
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ARCHITECTURAL STRUCTURES - GLOBAL MOMENT AND SHEAR
Global moments help to analyze not only a beam but also truss, cable or arch. They all resist global moments by a couple F times lever arm d:The force F is expressed as T (tension) and C (compression)...
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Portal Method For Rough Moment Frame Design
The Portal Method for rough moment frame design is based on these assumptions:• Lateral forces resisted by frame action• Inflection points at mid-height of columns• Inflection points at mid-span of...
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Structures: Bending, Effect of Overhang
Bending moments can be greatly reduced, using the effect of overhangs. This can be describe on the example of a beam but applies also to other bending members of horizontal, span subject to gravity...
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BEAM OPTIMIZATION
Optimizing long-span girders can save scares resources. The following are a few conceptual options to optimize girders. Optimization for a real project requires careful evaluation of alternate...
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Gerber Beam
The Gerber beam is named after its inventor, Gerber, a German engineering professor at Munich. The Gerber beam has hinges at inflection points to reduce bending moments, takes advantage of continuity,...
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Joist, Beam, Girder
Joists, beams, and girders can be arranged in three different configurations: joists supported by columns or walls1; joists supported by beams that are supported by columns2; and joists supported by...
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Vierendeels Configurations
Vierendeels may have various configurations, including one-way and two-way spans. One-way girders may be simply supported or continuous over more than two supports. They may be planar or prismatic with...
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Structures: Folded Plate
The effect of folding on folded plates can be visualized with a sheet of paper. A flat paper deforms even under its own weight. Folding the paper adds strength and stiffness; yet under heavy load the...
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