Norma Ecuatoriana De La Construccion
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Publicado: 25 de julio de 2012
ECUADORIAN CONSTRUCTION CODE 2002
SEISMIC HAZARD, DESIGN SPECTRA AND MINIMUM CALCULATION
EARTHQUAKE-RESISTANT DESIGN
6. DETERMINATION OF THE MINIMUM DESIGN LATERAL FORCES AND EFFECTS RELATED
6.1 General: The structures must be designed to resist seismic forces from
any horizontal direction. It can be assumed that the design seismic forces acting on a non-concurrent with the directionof the principal axis of the structure.
6.1.1 The reactive seismic load W by the end of this code, reactive load represents the quake, as the total dead load of the structure. In the case of structures of storage or warehouses, W calculated as the dead load plus 25% of the live load of floor.
6.1.2 The mathematical model of the structure include all the elements of the system resistantstructural and spatial distribution of masses and rigidities in the structure.
6.1.2.1 In the case of reinforced concrete structures, the calculation of rigidity shall be used values of inertia cracked Icr of structural elements, as follows: 0.5 Ig beams (considering the contribution of the slabs, where applicable) and 0.8 Ig columns, being Ig the value of the inertia of the uncrackedcross-section of element considered. In the case of structural walls, cracked inertia values take the value of 0.6 Ig and apply only in the first two floors of the building (for structures without basements) or in the first two floors and in the first basement (for structures with basements). For the remaining floors of the wall cracked inertia can be considered equal to the inertia uncracked.
6.1.2.2In the case of masonry structures, the value of the inertia cracked to be used for walls will be 0.5 Ig.
6.2 METHOD OF CALCULATION OF STATIC FORCES.-
6.2.1 Basal Shear Design: The total design base shear V, to be applied to a structure a given direction is determined by the expressions:
[pic]
where:
C = Do not exceed the value of Cm provided in Table 3, must not be less than 0.5 andmay used for any structure,
S = The value and its exponent are obtained from Table 3,
R = response reduction factor structural
ΦP, ΦE = coefficients of structural configuration in plan and elevation, respectively.
6.2.2 Coefficient of structural settings ΦP plant.
6.2.2.1 ΦP coefficient is estimated from the analysis of patterns of regularity and
irregularity of the plants in thestructure, described in Table 5 and Figure 2. Be used
expression:
[pic]
where:
ΦPA = The minimum value ΦPi of each floor i of the structure, from Table 5, for when irregularities are present type 1, 2 and / or 3 (ΦPi on each floor is calculated as the minimum value expressed by the table for the three irregularities)
ΦPB = is established similarly, for when irregularities are presenttype 4 and / or 5 in the structure.
When a structure does not provide any of the types of deficiencies described in Table 5, none of the floors, ΦP take the value 1.
6.2.3 Coefficient of structural configuration in elevation ΦE.
6.2.3.1 ΦE coefficient is estimated from the analysis of patterns of regularity and irregularity in elevation of the structure, described in Table 6 and Figure3. Be used expression:
[pic]
where:
ΦEA = The minimum value ΦEi of each floor i of the structure, from Table 6, for when
irregularities are present type 1 and / or 5 (ΦEi on each floor is calculated as the minimum value expressed by the table for two irregularities)
ΦEB = is established similarly, for when irregularities are present type 2 and / or 3 in the structure, ΦEC = Set towhere the deficiency is present in the structure type 4.
When a structure does not provide any of the types of deficiencies described in Table 6, any level, ΦE take the value 1.
Additionally, take into account that when the maximum drift of any floor is less than 1.3 times the drift of the story immediately above, can be seen that there are no irregularities in types 1, 2, or 3.
6.2.4...
SEISMIC HAZARD, DESIGN SPECTRA AND MINIMUM CALCULATION
EARTHQUAKE-RESISTANT DESIGN
6. DETERMINATION OF THE MINIMUM DESIGN LATERAL FORCES AND EFFECTS RELATED
6.1 General: The structures must be designed to resist seismic forces from
any horizontal direction. It can be assumed that the design seismic forces acting on a non-concurrent with the directionof the principal axis of the structure.
6.1.1 The reactive seismic load W by the end of this code, reactive load represents the quake, as the total dead load of the structure. In the case of structures of storage or warehouses, W calculated as the dead load plus 25% of the live load of floor.
6.1.2 The mathematical model of the structure include all the elements of the system resistantstructural and spatial distribution of masses and rigidities in the structure.
6.1.2.1 In the case of reinforced concrete structures, the calculation of rigidity shall be used values of inertia cracked Icr of structural elements, as follows: 0.5 Ig beams (considering the contribution of the slabs, where applicable) and 0.8 Ig columns, being Ig the value of the inertia of the uncrackedcross-section of element considered. In the case of structural walls, cracked inertia values take the value of 0.6 Ig and apply only in the first two floors of the building (for structures without basements) or in the first two floors and in the first basement (for structures with basements). For the remaining floors of the wall cracked inertia can be considered equal to the inertia uncracked.
6.1.2.2In the case of masonry structures, the value of the inertia cracked to be used for walls will be 0.5 Ig.
6.2 METHOD OF CALCULATION OF STATIC FORCES.-
6.2.1 Basal Shear Design: The total design base shear V, to be applied to a structure a given direction is determined by the expressions:
[pic]
where:
C = Do not exceed the value of Cm provided in Table 3, must not be less than 0.5 andmay used for any structure,
S = The value and its exponent are obtained from Table 3,
R = response reduction factor structural
ΦP, ΦE = coefficients of structural configuration in plan and elevation, respectively.
6.2.2 Coefficient of structural settings ΦP plant.
6.2.2.1 ΦP coefficient is estimated from the analysis of patterns of regularity and
irregularity of the plants in thestructure, described in Table 5 and Figure 2. Be used
expression:
[pic]
where:
ΦPA = The minimum value ΦPi of each floor i of the structure, from Table 5, for when irregularities are present type 1, 2 and / or 3 (ΦPi on each floor is calculated as the minimum value expressed by the table for the three irregularities)
ΦPB = is established similarly, for when irregularities are presenttype 4 and / or 5 in the structure.
When a structure does not provide any of the types of deficiencies described in Table 5, none of the floors, ΦP take the value 1.
6.2.3 Coefficient of structural configuration in elevation ΦE.
6.2.3.1 ΦE coefficient is estimated from the analysis of patterns of regularity and irregularity in elevation of the structure, described in Table 6 and Figure3. Be used expression:
[pic]
where:
ΦEA = The minimum value ΦEi of each floor i of the structure, from Table 6, for when
irregularities are present type 1 and / or 5 (ΦEi on each floor is calculated as the minimum value expressed by the table for two irregularities)
ΦEB = is established similarly, for when irregularities are present type 2 and / or 3 in the structure, ΦEC = Set towhere the deficiency is present in the structure type 4.
When a structure does not provide any of the types of deficiencies described in Table 6, any level, ΦE take the value 1.
Additionally, take into account that when the maximum drift of any floor is less than 1.3 times the drift of the story immediately above, can be seen that there are no irregularities in types 1, 2, or 3.
6.2.4...
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