# Changes for page Seismic analysis

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edited by IwonaBudny
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 ... ... @@ -17,7 +17,8 @@ 17 17 * the mass and mass distribution of the structure, 18 18 * the connection between the structure and ground, namely soil type. 19 19 20 -Another complicated problem is to define exact direction of the ground motion in the seismic investigation. Generally the ground movement is assumed as an arbitrary horizontal motion but the vertical motion also may cause problem to the structure. Fundamentally the calculation process can be divided into three methods: 20 +(% style="text-align: justify;" %) 21 +Another complicated problem is to define exact direction of the ground motion in the seismic investigation. Generally the ground movement is assumed as an arbitrary horizontal motion but the vertical motion also may cause problem to the structure. Fundamentally the calculation process can be divided into three methods. 21 21 22 22 (% id="HTimehistory" %) 23 23 == Time history == ... ... @@ -46,7 +46,7 @@ 46 46 Expected value of the maximal accelerations belongs to the individual periods which are prescribed in the national codes and named as acceleration response spectrum. The horizontal axis shows the frequency or vibration time of a single degree mass-spring system and the vertical axis shows the maximum corresponding acceleration. (In the Civil Engineering practice vibration period is used instead of frequency.) 47 47 48 48 (% style="text-align: justify;" %) 49 -The results which belong to the different ground motion directions and structural eigenfrequencies are summarized on the basis of the probability theory, which assumes that not all the effects appear in the same time. Most frequently used summation rule is the SRSS (Square Root of Sum of Squares). 50 +The results which belong to the different ground motion directions and structural eigenfrequencies are summarized on the basis of the probability theory, which assumes that not all the effects appear in the same time. Most frequently used summation rule is the **SRSS** (Square Root of Sum of Squares). 50 50 51 51 (% style="text-align: justify;" %) 52 52 Although the modal analysis is the most accepted method all over the world (as well as in EC8), it has some disadvantages. Some of them are listed as follows: ... ... @@ -80,14 +80,16 @@ 80 80 == National codes == 81 81 82 82 ((( 83 -(% style="text-align: justify;" %) 84 +(% class="box warningmessage" style="text-align: justify;" %) 85 +((( 84 84 Remarks in application of national codes: 85 85 86 -* before releasing the current version of FEM-Design, only the Eurocode and Norwegian national code contained special description for seismic calculation. In the other codes FEM-Design supports only the general mo- dal analysis, 88 +* before releasing the current version of FEM-Design, only the Eurocode and Norwegian national code contained special description for seismic calculation. In the other codes FEM-Design supports only the general modal analysis, 87 87 * most of the countries did not prepare the National Application Document (NAD) for the universal Eurocode, so the program uses the general pres-cription. 88 88 ))) 89 89 90 90 Supported national codes and methods: 93 +))) 91 91 92 92 |(% style="width:247px" %)British |(% style="width:1626px" %)Modal analysis 93 93 |(% style="width:247px" %)Code independent|(% style="width:1626px" %)Modal analysis ... ... @@ -111,8 +111,6 @@ 111 111 112 112 = **Input data** = 113 113 114 -Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. 115 - 116 116 (% id="HSub-paragraph-2" %) 117 117 == Dynamic calculations and Mass definitions == 118 118 ... ... @@ -441,7 +441,6 @@ 441 441 * E,,Ei,, is the value of this seismic action effect due to the vibration mode i, 442 442 * r,,ij,, is the interaction between two vibration periods taking into ac- count the declining ratio: 443 443 444 -(% class="wikigeneratedid" %) 445 445 == [[image:1536571049986-697.png||height="63" width="395"]] == 446 446 447 447 (% style="text-align: justify;" %) ... ... @@ -449,7 +449,6 @@ 449 449 450 450 T,,j ,,/ T,,i ,,> 0,9 with T,,j ,,≤ T,,i,, 451 451 452 -(% style="text-align: justify;" %) 453 453 454 454 455 455 FEM-Design always applies the selected rule for the summation except if the **Automatic **is highlighted. If the **Automatic **is selected then the rule selection procedure is as follows: ... ... @@ -465,7 +465,6 @@ 465 465 466 466 ---- 467 467 468 -(% class="wikigeneratedid" %) 469 469 == Other setting possibilities == 470 470 471 471 === Horizontal direction setting for seismic calculation === ... ... @@ -497,7 +497,6 @@ 497 497 498 498 ---- 499 499 500 -(% class="wikigeneratedid" %) 501 501 == Combination rule, rotation and second order effects == 502 502 503 503 (% style="text-align: justify;" %)