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TECHNICAL PAPER

been computed as 428.8 kN, 465.4 kN, and 3826.5 kN, respectively. BRB core sizes are computed using the procedure discussed in
the preceding sections. Table 1 summarizes the sizes of BRB core segments in 4-story, 8-story and 20-story strengthened frames. The
[22]
values of β, ơ yBRB, Es are considered as 1.1, 248 MPa, 200 GPa, respectively . Moreover, axial stiffness, K BRB, of BRBs are computed
assuming the core lengths equal to 70% of their total lengths.

(4-Story)
(4-Story)

(8-Story)

(8-Story)

(20-Story) (20-Story)
Figure 4: Elevation and cross-section details of members of 4-story, 8-story, and 20-story RC frames strengthened using BRBs at the ground story level.
The expected axial tensile yield strengths (P yt) of BRBs are values of expected axial resistance and displacements of BRBs in
computed as the product of material overstrength factor (R y) all strengthened frames are summarized in Table 2.
and the nominal yield strengths (i.e., A BRBơ yBRB). The value of R y is
considered as 1.1. The expected axial compressive strength (P yc) 4.2 numerical Modelling
of BRBs is computed as the compression adjustment factor (β) Both linear and nonlinear analyses are conducted for the
times the yield strength (P yt). The expected ultimate strengths strengthened frames using a computer software SAP2000 .
[23]
(i.e., Put and Puc) are computed as the tension adjustment Lumped-plasticity approach is adopted to model the nonlinear
factor (ω) times the corresponding yield strengths (i.e., P ut and behaviour of members. All beam and columns of the study
P uc). The displacement values corresponding to tension and frames are modelled as the frame elements. Flexural, shear and
compression yield points are computed by dividing the yield axial force behaviour and their interactions of frame members
strengths of BRBs by their axial stiffness (K BRB). The computed

The IndIan ConCreTe Journal | november 2019 27