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This page is devoted to frequently asked questions (FAQ) related to acceleration. |
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General
What is the difference between relative and absolute acceleration?
ANSWER: Relative acceleration is within the reference frame local to the structure. Absolute acceleration is within a universal reference frame, and is given as the sum of relative acceleration and ground acceleration. The same relative and absolute designations also apply to velocity and displacement.
The Display > Show Plot Functions menu presents options for either relative or absolute absolute acceleration. Relative acceleration
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Related Incidents:
Alternate explanation: Relative displacement is within the reference |
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system local to the structure. Absolute |
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displacement is within a universal reference |
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system and is given as the sum of relative |
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displacement and ground |
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displacement. |
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In other words, the relative displacement is displacement of joints on the structure relative to the displacement of the foundation joints. Absolute displacements are measured from a fixed point located far away on the ground that is not affected by the earthquake. |
Is acceleration load only applied to selected members?
ANSWER: No. CSI software automatically generates and envelopes a set of acceleration loads for translation along, and rotation about, each global axis. These acceleration loads are applied at each node and object to simulate ground motion during time-history and translation-only response-spectrum analyses.
Acceleration loads may be manually assigned to specific nodes and objects, then applied through a load case. Acceleration loads in the program are included as a percentage of gravity, g. Therefore, to manually assign acceleration loads to selected members, first divide the acceleration by g. Then enter the percentage in the Scale Factor box in the Loads Applied area of the Load Case Data form.
Formulation
How is acceleration load calculated and applied?
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