Overstrength Factor – NTC 2017

SASID System Parameters Sec. 3.1

T_a Lower characteristic period

T_b Upper characteristic period

T_s Site dominant period

Parameters T_a, T_b y T_s are obtained from SASID (Sistema de Acciones Sísmicas de Diseño — Mexico City seismic design actions system) at www.sasid.df.gob.mx for the specific location of the site.

Structural System Parameters Sec. 3.5

R₀ Basic overstrength factor

R₀ = 2.0 — For structures of masonry, and for structural systems of concrete, steel or composite that meet the requirements to adopt a behaviour factor Q of 3 or greater, per the rules in Chapter 4.

R₀ = 1.75 — For structural systems of concrete, steel or composite assigned a Q lower than 3 per the rules in Chapter 4.

R₀ = 1.25 — For the dual structural systems included in tables 4.2.1 and 4.2.2 of the NTC.

k₁ Redundancy correction factor

k₁ = 0.8 — For systems of concrete, steel or composite having fewer than three bays resisting seismic load in the direction of analysis, and two or fewer resisting bays in the direction normal to it.

k₁ = 1.0 — For structures of masonry, and for concrete, steel or composite structural systems having three or more bays resisting seismic load in both directions of analysis.

k₁ = 1.25 — For the dual structural systems included in tables 4.2.1 and 4.2.2 of the NTC (the same systems that adopt R₀ = 1.25).

Calculated Parameters · Table 3.1.1 Ec. 3.1.1

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K_s

Ec. 3.1.1

—

T (Table 3.1.1)

Dominant period

—

λ (lambda)

Table 3.1.1

Table 3.1.1 — Values of λ, ε and τ as a function of T_s · The highlighted row corresponds to the T_s entered

Site period T_s (s)		λ	ε	τ (T)

Equation 3.5.1 Factors

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R₀

Basic factor

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k₁

Redundancy

—

k₂

Ec. 3.5.2

Calculation Development

Overstrength Factor

—

R = k₁·R₀ + k₂ = —

Calculation Report

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Factor de Factor

Calculation Report