# Changes for page Seismic analysis

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edited by IwonaBudny
on 2018/09/10 13:20
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 ... ... @@ -60,10 +60,10 @@ 60 60 Despite of all disadvantages of this method, we can expect most trustable results if the code requirements are fulfilled. 61 61 62 62 (% id="HLateralforcemethod" %) 63 -== Lateral force method (Equivalent static load method) == 63 +== Lateral force method == 64 64 65 65 (% style="text-align: justify;" %) 66 -The lateral force method partly eliminates the disadvantages of the previous method with simplification in certain cases. The method postulates that the dis- placement response of the structure for ground motion can be described with one (or both x', y' directions) mode shape. While this means generally a simplification or approximation, this method is suitable for a part of the structure (EC8 prescribes the condition of application). In this method the mode shape of the structure is a linear deviation or it is equivalent to the calculated fundamental vibration shape. In the case of linear deviation or mode shape the period also can be calculated by approximate formula. 66 +The lateral force method called also Equivalent static load method, partly eliminates the disadvantages of the previous method with simplification in certain cases. The method postulates that the dis- placement response of the structure for ground motion can be described with one (or both x', y' directions) mode shape. While this means generally a simplification or approximation, this method is suitable for a part of the structure (EC8 prescribes the condition of application). In this method the mode shape of the structure is a linear deviation or it is equivalent to the calculated fundamental vibration shape. In the case of linear deviation or mode shape the period also can be calculated by approximate formula. 67 67 68 68 (% style="text-align: justify;" %) 69 69 The application of this method gives possibility to transform the seismic lateral forces to simple static loads and it is applicable as follows: ... ... @@ -420,7 +420,7 @@ 420 420 ))) 421 421 422 422 423 -=== Modal response spectrum analysis (modal analysis) === 423 +=== Modal response spectrum analysis === 424 424 425 425 (% style="text-align: justify;" %) 426 426 This method can be used in all national codes. ... ... @@ -479,7 +479,7 @@ 479 479 480 480 == Other setting possibilities == 481 481 482 -=== Horizontal direction setting for seismic calculation === 482 +=== Horizontal direction setting === 483 483 484 484 Generally codes speak about the seismic calculation in X-Y directions. However results in these directions give the maximum effect if the mass and elastic properties of the structure ensure that the calculated mode shapes lay in X-Z or Y-Z plane. Nevertheless it is not always achieved in practice. To achieve the unfavorable direction, where the results from a ground motion are maximum, the user can Set the Alpha angle or may get the program suggestion by using Auto but- ton. 485 485