Changes for page Seismic analysis

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edited by IwonaBudny
on 2018/09/06 15:00
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 ... ... @@ -284,4 +284,26 @@ 284 284 285 285 = **Useful tips, which method to use?** = 286 286 287 - 287 +((( 288 +(% style="text-align: justify;" %) 289 +To answer this question is hard even for experienced engineers. However some basic concept can be formulated: 290 + 291 +(% class="box successmessage" %) 292 +((( 293 +Before any decision, always run the Eigenfrequencies calculation. From these results you will experience how the structure behaves in aspect of dynamics. 294 + 295 +Always check the effective masses, if you calculate the structure for seismic effect in the first occasion or make changes in the geometry or in the mass distribution. 296 + 297 +If you see that the effective masses shows larger value than 100% com- pare them to the Total mass and not to the Reduced mass. 298 + 299 +If the sum of the selected effective masses is less than the prescribed minimum (in EC8 this is 90%), calculate more mode shape. 300 + 301 +If the sum of effective masses in case of large number mode shapes doesn’t approach to the prescribed value use the static, linear shape or static, mode shape if the code allow. 302 + 303 +If the building has large importance or it has special geometry try to apply the modal analysis. 304 + 305 +If the building is not too high, any of the static methods will give reliable results avoiding longer run time calculation in eigenfrequencies. 306 + 307 +It is not always necessary to analyze the 3D model in all directions, sometimes one or two planar model is enough. 308 +))) 309 +)))