algerian earthquake resistant regulations Â« rpa 99 - IISEE

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The concentrated force F t at the top of the structure allows to take into account the influence of the high vibration modes of the structure. It is determined by the formula: F t = 0.07 TV Where T is the fundamental period of the structure (in second). The value of F t should not exceed 0,25 V and should be taken equal to 0 when T is smaller or equal to 0.7 seconds The differential part of V, i.e., (V - F t ) should be distributed following the height of the structure following the formula: (V − F t ) Whi Fi = (4.11) n W h ∑ j= 1 4.2.6 Horizontal distribution of the seismic forces j j The shear force at the level k: V = F + F (4.12) k t n ∑ i= k i in the case of structures comprising rigid floors in their plan, is distributed to vertical elements of the resisting system proportionally to their relative stiffness. 4.2.7 Torsion Effect The increasing of the shear force provoked by the horizontal torsion due to the eccentricity between the center of gravity and the center of rigidity should be taken into account. The negative shear forces due to the horizontal torsion should be neglected. For all structures having rigid floors or diaphragms in their plan, it is supposed that at each level and in each direction, the global horizontal force has an eccentricity in comparison with the torsion center equals to the greater of the two values: -5% of the greatest dimension of the building at this level (this eccentricity should be considered on either side of the center of torsion) -Theoretical eccentricity given by the schemes. 4.3. MODAL RESPONSE SPECTRUM ANALYSIS METHOD 4.3.1. Principle By this method, the objective is to assess for each vibration mode, the maximum effects generated in the structure by the seismic forces represented by a design response spectrum. These effects are thereafter combined to obtain the response of the structure. 4.3.2. Modelling a) For regular structures in plan with rigid floors, the analysis is made separately in each of the two main directions of the building. The building is then represented in each of the two directions of calculation by a plan model, embeded at the basis and where masses are concentrated in the gravity centers of the floors and considering only one DOF in horizontal displacement. b) For irregular structures in plan, subject to horizontal torsion and having rigid floors, they are represented by a tridimensional model, embeded at the base and where masses are 1-30
concentrated in the gravity centers of floors considering three (03) DOF (2 horizontal motions and a rotational motion) c) For structures, regular or not, comprising flexible floors, they are represented by the tridimensional modals embeded at the base and considering several DOF by floor. d) The deformability of the soil of foundation should be taken into account in the model in all the cases where the response of the structure depends significantly on it. e) The model of building to use should represent to the better the distribution of rigidities and masses so that to take into account all significant deformation modes in the calculation of the seismic forces (ex: contribution of the nodal zones and non-structural elements to the rigidity of the building). f) In case of Reinforced Concrete or Masonry Buildings, the rigidity of vertical resisting elements should be calculated taking into account non-cracked transversal sections. If displacement is critical particularly in the case of structures associated with high values of the behavior coefficient, a more precise estimation of the rigidity becomes necessary and cracked transversal sections must be accounted for. g) To take into account uncertainties on the position of masses and the spatial variation of the seismic motion, an accidental eccentricity (0.05 L, L being the dimension of the perpendicular direction to the seismic action) should be applied in the same direction in addition to structural eccentricity. 4.3.3 Design Response Spectrum The seismic action is represented by the following Design Response Spectrum Sa g Sa g Sa g Sa g ⎛ T1 ⎛ Q ⎞⎞ = 1.25A⎜1 + ⎜2.5η −1⎟⎟ ⎝ T ⎝ R ⎠⎠ ⎛ Q ⎞ = 2.5η ⎜1.25A ⎟ ⎝ R ⎠ ⎛ Q ⎞⎛ T2 ⎞ = 2.5η ⎜1.25A ⎟⎜ ⎟ ⎝ R ⎠⎝ T ⎠ ⎛ Q T2 2.5 ⎜ ⎛ ⎞ = η 1.25A ⎜ ⎟ ⎜ R 3 ⎝ ⎝ ⎠ 2 3 2 3 5 3 ⎛ 3 ⎞ ⎜ ⎟ ⎝ T ⎠ ⎞ ⎟ ⎟ ⎠ T ≤ T ≤ T T 2 0 ≤ T ≤ T 1 ≤ T ≤ 3.0s T ≥ 3s 2 1 (4.13) A: Zone acceleration coefficient (table 4.1) η: factor of correction of damping (when the damping is different of 5%) η = (4.3) ξ: percentage of critical damping (table 4.2) R: behavior coefficient of the structure (table 4.3) T1, T2: characteristic periods associated with the site category (table 4.7) Q: factor of quality (table 4.4) 1-31
Page 1 and 2: ALGERIAN EARTHQUAKE RESISTANT REGUL
Page 3 and 4: CHAPTER II - GENERAL RULES FOR CONC
Page 5 and 6: 2.5.2. Joints The laying out of the
Page 7 and 8: CHAPTER III . CLASSIFICATION CRITER
Page 9 and 10: 3.2. CLASSIFICATION OF THE CONSTRUC
Page 11 and 12: Table 3.2. : Classification of site
Page 13 and 14: The site conditions that need detai
Page 15 and 16: It is a system where 50% or more of
Page 17 and 18: 13. Steel frame structure braced by
Page 19 and 20: Fig. 3.2 : Limits of the plan setba
Page 21 and 22: structure under effects of a major
Page 23 and 24: 1-25
Page 25 and 26: B 7 8 9a 9b 10a 10b 11 Steel Ductil
Page 27: Tableau 4.6: values of the coeffici
Page 31 and 32: ) In the case where all considered
Page 33 and 34: CHAPTER V: SAFETY VERIFICATION 5.1.
Page 35 and 36: 5.9. P-Δ. EFFET Second order effec
Page 37: 8.1 GENERAL 8.2 DUCTILE MOMENT RESI

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