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From version < 40.4 >
edited by IwonaBudny
on 2018/09/10 12:22
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edited by IwonaBudny
on 2018/09/10 12:55
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... ... @@ -118,11 +118,11 @@
118 118  == Dynamic calculations and Mass definitions ==
119 119  
120 120  (% style="text-align: justify;" %)
121 -[[image:1536237300428-654.png||height="27" width="66"]] To calculate the seismic effect it is necessary to know the vibration shapes and corresponding periods, except the static method (lateral force method: linear force distribution). Therefore a dynamic calculation should be done before performing seismic calculation, which gives sufficient vibration shapes of the structure. To perform the dynamic calculation, it is necessary to define mass distribution which can be defined in Load tab as concentrated mass or load case-mass conversion.
121 +To calculate the seismic effect it is necessary to know the vibration shapes and corresponding periods, except the static method (lateral force method: linear force distribution). Therefore, a dynamic calculation should be done before performing seismic calculation, which gives sufficient vibration shapes of the structure. To perform the dynamic calculation, it is necessary to define mass distribution which can be defined in Load tab as concentrated mass or load case-mass conversion.
122 122  
123 -According to EC8 3.2.4(2), mass distribution should be made in the following way:
123 +[[image:1536237300428-654.png||height="27" width="66"]] According to EC8 3.2.4(2), mass distribution should be made in the following way:
124 124  
125 -(% class="mark" %)&Sigma;G,,k,,, ,,j,,"" + ""&Sigma;ψ,,E, i,,Q,,k, i ,,
125 +(% class="mark" %)&Sigma;Gk, j"" + ""&Sigma;ψE, iQk, i
126 126  
127 127  where:
128 128  
... ... @@ -130,6 +130,7 @@
130 130  
131 131  (% class="mark" %)ψ,,E, i ,,= ϕ ψ^^2, ^^i
132 132  
133 +
133 133  The recommended values for ϕ are listed in EC8 Table 4.2.
134 134  
135 135  The above formula means that mass conversation is made from all dead load without any factor, also masses in gravity direction temporary loads with reduced value.
... ... @@ -140,12 +140,14 @@
140 140  (% style="text-align: justify;" %)
141 141  [[image:1536237268175-179.png||height="23" width="26"]] The program contains EC8 and NS3491-12 predefined design spectra or the user can define its own spectra if necessary. The vertical spectrum is necessary when the vertical affect taken into account.
142 142  
143 -=== (% style="font-size:18px" %)**EC8 design spectrum**(%%) ===
144 +(% id="HEC8designspectrum" %)
145 +=== EC8 design spectrum ===
144 144  
145 145  The code gives the horizontal and vertical spectra and although the value of variables is prescribed, they can be modified if necessary.
146 146  
147 147  [[image:1536237376815-771.png||height="247" width="315"]]
148 148  
151 +
149 149  **Horizontal spectra**
150 150  
151 151  Data of horizontal design spectra:
... ... @@ -183,11 +183,12 @@
183 183  (% style="text-align: justify;" %)
184 184  In the Others tab, the user should set some parameters that effect the calculation and results.
185 185  
186 -* Ksi(ξ) is the viscous damping ratio, expressed as a percentage, gene- rally 5%. This data is used in modal analysis when the sum- mation of the effect of the same direction vibration shapes is carried out by the CQC (Complete Quadratic Combination), see later.
187 -* qd is the displacement behavior factor, assumed equal to q unless otherwise specified.
188 -* Foundation level when Static-linear shape is used, the program assumes that the foundation level is defined on that height. It means the pro- gram calculates the mass height from that level. In the other two calculation methods (Static-mode shape and Modal analysis) base shear force is drawn in that level and it is taken into consideration in the so called reduced mass calculation (details in Effective mass setting).
189 +* Ksi(ξ) is the viscous damping ratio, expressed as a percentage, gene- rally 5%. This data is used in modal analysis when the sum- mation of the effect of the same direction vibration shapes is carried out by the CQC (Complete Quadratic Combination), see later.
190 +* qd is the displacement behavior factor, assumed equal to q unless otherwise specified.
191 +* Foundation level when Static-linear shape is used, the program assumes that the foundation level is defined on that height. It means the pro- gram calculates the mass height from that level. In the other two calculation methods (Static-mode shape and Modal analysis) base shear force is drawn in that level and it is taken into consideration in the so called reduced mass calculation (details in Effective mass setting).
189 189  
190 -=== (% style="font-size:18px" %)**NS3491-12 design spectrum**(%%) ===
193 +(% id="HNS3491-12designspectrum" %)
194 +=== NS3491-12 design spectrum ===
191 191  
192 192  **Horizontal spectra**
193 193  
... ... @@ -208,6 +208,7 @@
208 208  * S,,e,,(T,,i,,) is the acceleration for the period Ti in the normalized response spectra, see below,
209 209  * k,,f,spiss,, is a factor dependent on the reference period used.
210 210  
215 +
211 211  **Vertical spectra**
212 212  
213 213  [[image:1536238363669-269.png||height="32" width="119"]]
... ... @@ -223,6 +223,7 @@
223 223  * k,,ν,, is the ratio between horizontal and vertical response spectra, mostly set to 0,7.
224 224  
225 225  (% style="text-align: justify;" %)
231 +
226 226  The normalized response spectrum in Norwegian code is based on four different formulas, each covering a part of the possible periods from 0 to 4 seconds. Periods over 4 seconds has to be treated in a different way anyhow, and can therefore be based on a manually written response spectrum.
227 227  
228 228  (% style="text-align: justify;" %)
... ... @@ -247,7 +247,8 @@
247 247  
248 248  In the NS3491-12 code only foundation level should be set.
249 249  
250 -=== (% style="font-size:18px" %)**Design spectra in the other national codes**(%%) ===
256 +(% id="HDesignspectraintheothernationalcodes" %)
257 +=== Design spectra in the other national codes ===
251 251  
252 252  Except for the above mentioned two codes, the user has in all cases to define the spectra in table or in a graphical way. In the Others tab only the foundation level should be set.
253 253  
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