Seismic Design of Structures and Components in Industrial Units

Abstract

Industrial units consist of the primary load-carrying structure and various process engineering components, the latter being by far the most important in financial terms. In addition, supply structures such as free-standing tanks and silos are usually required for each plant to ensure the supply of material and product storage. Thus, for the earthquake-proof design of industrial plants, design and construction rules are required for the primary structures, the secondary structures and the supply structures. Within the framework of these rules, possible interactions of primary and secondary structures must also be taken into account. Importance factors are used in seismic design in order to take into account the usually higher risk potential of an industrial unit compared to conventional building structures. Industrial facilities must be able to withstand seismic actions because of possibly wide-ranging damage consequences in addition to losses due to production standstill and the destruction of valuable equipment. The chapter presents an integrated concept for the seismic design of industrial units based on current seismic standards and the latest research results. Special attention is devoted to the seismic design of steel thin-walled silos and tank structures.

Annex: Tables of the Pressure Components

See Tables 5.20, 5.21, 5.22, 5.23, 5.24, 5.25, 5.26, 5.27 and 5.28.

Table 5.20 Coefficient ${\mathbf{C}}_{{\mathbf{k}}}$ for the convective pressure component considering the fundamental natural mode for sloshing; to be multiplied with ${\mathbf{R}} \cdot {\varvec{\rho}}_{{\mathbf{L}}} \cdot \,{\mathbf{cos}}\left( {\varvec{\theta}} \right) \cdot {\mathbf{a}}_{{\mathbf{k}}} ({\mathbf{t}} ) \cdot \,{\varvec{\Delta}}_{{\mathbf{k}}}$, where ${\mathbf{a}}_{{\mathbf{k}}}$ = horizontal spectral acceleration at the fundamental period T_k1 according to Eq. (5.42)

Table 5.21 Coefficient ${\mathbf{C}}_{{{\mathbf{is,h}}}}$ for the impulsive rigid pressure component due to horizontal seismic excitation; approximation of the Bessel function with a series of 200 terms; to be multiplied with ${\mathbf{R}} \cdot {\varvec{\rho}}_{{\mathbf{L}}} \cdot \,{\mathbf{cos}}\left( {\varvec{\theta}} \right) \cdot {\mathbf{a}}_{{{\mathbf{is,h}}}} ({\mathbf{t}} ) \cdot \,{\varvec{\Gamma}}_{{{\mathbf{is,h}}}}$, where ${\mathbf{a}}_{{{\mathbf{is,h}}}}$ = horizontal spectral acceleration at period T = 0 (free field acceleration)

Table 5.22 Coefficient ${\mathbf{C}}_{{{\mathbf{if}},{\mathbf{h}}}}$ for the impulsive flexible pressure component due to horizontal seismic excitation; approximation of the Bessel function with a series of 100 terms; to be multiplied with ${\mathbf{R}} \cdot {\varvec{\rho}}_{{\mathbf{L}}} \cdot \,{\mathbf{cos}}\left( {\varvec{\theta}} \right) \cdot {\mathbf{a}}_{{{\mathbf{if,h}}}} ({\mathbf{t}} ) \cdot \, {\varvec{\Gamma}}_{{{\mathbf{if,h}}}}$, where ${\mathbf{a}}_{{{\mathbf{if,h}}}}$ = horizontal spectral acceleration at the fundamental period T_if,h,1 calculated with an FE model or according to Eq. (5.50)

Table 5.23 Coefficient ${\mathbf{C}}_{{{\mathbf{if}},{\mathbf{h}}}}$ for the impulsive flexible pressure component due to horizontal seismic excitation; bending curve approximated with a parametrized sine function according to Eq. ( 5.54 ); to be multiplied with ${\mathbf{R }} \cdot {\varvec{\rho}}_{{\mathbf{L}}} \cdot \,{\mathbf{cos}}\left( {\varvec{\theta}} \right) \cdot {\mathbf{a}}_{{{\mathbf{if,h}}}} ({\mathbf{t}} ) \cdot \,{\varvec{\Gamma}}_{{{\mathbf{if,h}}}}$, where ${\mathbf{a}}_{{{\mathbf{if,h}}}}$ = horizontal spectral acceleration at the fundamental period T_if,h,1 calculated with an FE model or according to Eq. (5.50)

Table 5.24 Coefficient ${\mathbf{C}}_{{{\mathbf{if,v}}}}$ for the impulsive flexible pressure component due to vertical seismic excitation; Bending curve: ${\mathbf{f}}\left( {\varvec{\zeta}} \right) { = }{\mathbf{cos}}\left( {{\varvec{\pi}} /{\mathbf{2}} \cdot {\varvec{\zeta}}} \right)$; including the correction factor to consider the degree of clamping at the tank bottom according to Eq. (5.66); values of the correction factor β for slenderness values γ > 4 have to be checked carefully; the coefficient ${\mathbf{C}}_{{{\mathbf{if,v}}}}$ is to be multiplied with ${\mathbf{R}} \cdot {\varvec{\rho}}_{{\mathbf{L}}} \cdot {\mathbf{a}}_{{{\mathbf{if,v}}}} ({\mathbf{t}} ) \cdot {\varvec{\Gamma}}_{{{\mathbf{if,v}}}}$, where ${\mathbf{a}}_{{{\mathbf{if,v}}}}$ = spectral acceleration of the joint rotationally symmetric fundamental natural mode with the fundamental natural period T_if,v,1 calculated with an FE model or according to Eq. (5.63)

Table 5.25 Correction factor β to consider the clamping degree at the tank bottom. The factor is already considered in Table 5.24

Table 5.26 Participation factor $\Gamma_{{if,v}}$ for the impulsive flexible pressure component due to vertical seismic excitation

Table 5.27 Coefficients ${\mathbf{C}}_{{{\mathbf{F}},{\mathbf{j}}}} ,\varvec{ } {\mathbf{C}}_{{{\mathbf{MW}},{\mathbf{j}}}} ,\varvec{ }{\mathbf{C}}_{{{\mathbf{MB}},{\mathbf{j}}}} ,\varvec{ }{\mathbf{C}}_{{{\mathbf{M}},{\mathbf{j}}}} \varvec{ }$ and participation factors Γ_j for the convective (j = k), impulsive rigid (j = is, h) and impulsive flexible pressure components (j = if, h)

Table 5.28 Coefficients ${\mathbf{C}}_{{{\mathbf{F}},{\mathbf{if}},{\mathbf{h}}}} ,\varvec{ } {\mathbf{C}}_{{{\mathbf{MW}},{\mathbf{if}},{\mathbf{h}}}} ,\varvec{ }{\mathbf{C}}_{{{\mathbf{MB}},{\mathbf{if}},{\mathbf{h}}}} ,\varvec{ }{\mathbf{C}}_{{{\mathbf{M}},{\mathbf{if}},{\mathbf{h}}}} \varvec{ }$ and participation factor Γ_if,h for the impulsive flexible pressure component; parametrized sine function of the bending curve according to Sect. 5.6.3.3