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The point within a planar area that corresponds to the center of gravity is called the centroid of the area. True False - Answer True Which of the following is NOT true about the basic cross-sectional properties of a beam? Material density can be ignored when calculating the centroid for homogeneous members with constant thickness The centroid is sometimes referred to as "the moment of an area" A member oriented as a plank, as opposed to a rafter, has 8 times more resistance to deflection The method for finding centroids is based on the method of determining the resultants of parallel force systems - Answer A member oriented as a plank, as opposed to a rafter, has 8 times more resistance to deflection The centroid of a triangle is located at which point along the length of the base, b? - Answer b / 3 Which of the following is NOT true about the process for calculating centroids? - Answer A convenient reference origin is often the upper right corner of the composite shape Which of the following is NOT true about the moment of inertia? The moment of inertia is sometimes referred to as "the second moment of an area" Moment of inertia measures the ability of a beam's cross-sectional shape to resist bending and deflection Moment of inertia is a measure of cross-sectional stiffness A beam with a small moment of inertia will have smaller stresses and deflections than one with a larger I-value - Answer A beam with a small moment of inertia will have smaller stresses and deflections than one with a larger I-value Members wtih larger moments of inertia will always have larger cross-sectional areas True False - Answer False
Which of the following equations is used to calculate the moment of inertia for a triangular shape? bh3 / 12 bh3 / 24 bh3 / 36 bh3 / 48 - Answer bh3 / 36 Which of the following is NOT true about the parallel axis theorom? The parallel axis theorom is used to compute the moment of inertia for a shape about any axis parallel to the centroidal axis A negative distance from the centroidal axis has a negative effect on the composite moment of inertia The parallel axis theorom is typically used for calculating the moment of inertia for composite areas It is necessary to know the location of the centroid of a shape before solving the moment of inertia - Answer A negative distance from the centroidal axis has a negative effect on the composite moment of inertia The radius of gyration is a cross-sectional property that is used in structural beam design. True False - Answer False Which of the following wide flange beam sections has the largest moment of inertia? W 33- W 27- W 30- W 24-162 - Answer W 30- Which of the following beam classifications is used to identify a beam with two supports, where one end is fixed? (pg. 333) Simply Supported Cantilever Propped
moment diagrams? (pg. 349) A zero-degree curve represents a straight horizontal line A first-degree curve represents a straight sloped line that may be increasing or decreasing
A second-degree curve is parabolic in shape
A third-degree curve is generally shallower than a second-degree curve - Answer A third-degree curve is generally shallower than a second-degree curve
Which of the following is NOT true about the endpoint properties of shear and moment diagrams? (pg. 351)
The shear must equal the end reaction at the location of simply supported beam ends
The moment must be zero at the location of simply supported beam ends
Both the shear and the moment are zero at the free end of a cantilever beam
The moment must be zero at the location of a fixed beam end - Answer The moment must be zero at the location of a fixed beam end
Which of the following is NOT true about the properties of a shear diagram? (pg. 351)
A concentrated force produces an abrupt change in shear
A uniformly distributed load acting downward produces a positive slope in the shear diagram
The change in shear between any force is equal to the concentrated force
The change in shear between any two sections is given by the area under the load diagram for the same two sections - Answer A uniformly distributed load acting downward produces a positive slope in the shear diagram
Which of the following is NOT true about the properties of a moment diagram? (pg. 351)
A positive area on the shear diagram causes a corresponding negative slope on the moment diagram
The slope at any point on the moment diagram is given by the shear at the corresonding onit on the shear diagram
The change in moment between any two sections is given by the area under the shear diagram for the same two sections
A moment applied to a beam will cause the moment diagram to change abruptly by the same amount - Answer A positive area on the shear diagram causes a corresponding negative slope on the moment diagram
