how to get an envelope combination in midas civil

However, the mass participation of subgrade levels may be subtracted from the total mass. RSA application How is response-spectrum analysis applied only above grade?Īnswer: During response-spectrum analysis, loading is applied to the entire structure, though sub-grade modes will have much higher frequencies, providing minimal contribution to modal response.

Additional information is available in the Damping in response-spectrum analysis article. Modal damping ratio may be increased such that damping increases without the need to change the response-spectrum function.

Display the output table by selecting Analysis Results > Structure Output > Named Set Data.Ĭan damping be changed without modifying the response-spectrum function?Īnswer: Yes, the response-spectrum function damping ratio and modal damping ratio may be specified.Use the interactive database editor to create the remaining Named Sets, one for each plot, by editing the tables within Model Definition > Other Definitions > Named Sets.Define one response-spectrum curve, then save the definition by selecting Save Named Set.How are multiple response-spectrum curves defined?Īnswer: Multiple response-spectrum curves may be defined using Named Set and interactive database editing to generate results in tabular format. Scale factor should be specified such that its product with response-spectrum values generates the acceleration units desired.įor example, if acceleration for the response-spectrum function is plotted as a fraction of gravitational acceleration, and if length units are in feet, then U1, U2, and U3 should be scaled by 32.2 units.

RSA definition What value of scale factor should be entered in the definition of a response spectrum load case?Īnswer: When the response-spectrum curve is defined, acceleration is typically entered as a fraction of gravitational acceleration (9.81 m/sec 2 or 32.2 ft/sec 2).

How to get an envelope combination in midas civil