Specifying Buckling-Restrained Brace Systems steelwise. Using the ductility of steel effectively in concentrically braced frames. ThE TERM. Buckling restrained braces (BRBs) are composed of a slender steel core, continuously supported by a concrete casing in order to prevent buckling under axial compression. The core and the casing are decoupled to prevent interaction between them. This paper presents a summary of buckling-restrained braces (BRBs). BRBs show the same load-deformation behavior in both compression and tension and.


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Buckling-restrained brace - Wikipedia

However, one-story high inelastic shear wall elements were used over the plastic hinge length based on section 6. The flexural strength at the plastic hinge buckling restrained braces should be as low as possible to allow early yielding of the wall, but at the same buckling restrained braces plastic hinge rotation as well as related deformation demands such as story drift and racking shear deformation should be within permissible limits.

In this study, flexural buckling restrained braces is based on the DBE design moment demands determined by code based procedure of UBC [ 1 ]. There are mainly two reasons for setting flexural strength in this way: Plastic hinges are also induced at both ends of coupling beams.

The characteristics of the plastic hinges are determined by beam cross section properties and flexural reinforcement worked out buckling restrained braces on the design demands and assumed plastic hinge length of 0.

The remaining portion of the coupling beam is modelled as elastic beam element.

A trilinear moment-curvature relationship without stiffness buckling restrained braces strength degradation is used for modelling plastic hinges at the ends of coupling beams.

All slabs and columns are modelled by elastic slab and column elements of the Perform-3D, respectively. The ground motions include both short distance moderate and long distance large magnitude earthquake.


The selected ground motions are first roughly scaled up or down by a constant factor to approximately match the target MCE spectrum. The roughly scaled ground motions buckling restrained braces then matched to the MCE target spectrum by using time domain spectral matching technique of [ 32 ].

The software RSP match [ 33 ] is used for this buckling restrained braces. The target spectrum and spectra of seven spectrally matched time history used in this study are shown in Figure 2. Analysis of Structure without BRBs The controlled structure described in Section 3 is analysed for seven sets of ground motions.

The shear and moment demands obtained are shown in Figure 5. Similarly, moment demand is also very high at mid height. However at the buckling restrained braces, the moment demand is clipped to the flexural strength of plastic hinge.


If the wall is designed for mid height moment to remain elastic and hence no damage, there shall be reinforcement congestion. On the other hand, if plastic hinge is allowed at mid height, the core wall shall be subjected to high rotational demands and hence damage near the mid height of the wall in addition to the base.

To reduce damage at the base of the wall as well as reduce mid height moment to avoid reinforcement congestion, an alternative strategy using different arrangements of buckling restrained braces energy dissipating devices has been evolved in the next section Options-2—4 and results are compared with the controlled structure Option Inelastic MCE shear and moment demands in the controlled buckling restrained braces.

Buckling Restrained Brace An ordinary buckling restrained braces exhibits unstable hysteretic behaviour due to buckling in compression; hence it cannot dissipate much energy.

Buckling-restrained brace

To avoid compression buckling and to achieve more energy dissipation, another brace known as buckling restrained brace BRB has been introduced. This type of brace exhibits stable hysteric behaviour because its compression buckling is avoided due to encasing by an outer steel tube.

The main brace buckling restrained braces outer tube are separated by bonding material in order to accommodate the lateral expansion due buckling restrained braces its compression yielding [ 37 ].


A typical BRB is shown in Figure 6 [ 38 ]. Location of Buckling Restrained Braces BRBs have been installed at several critical locations based on the buckling restrained braces of elastic modal decomposition analysis in dominant modes such as 1st, 2nd, and 3rd modes and results are compared with controlled structure described in Section 4 Option In second option Option-2the BRBs have been installed at bays 2, 3, buckling restrained braces 4 between peripheral columns and central core wall based on the maximum racking shear deformation demands in 2nd and 3rd modes.

This arrangement is shown in Figure 7. In third option, small size BRBs have also been installed at bays 2 and 4 in cut in central core wall at the maximum moment demands in 2nd and 3rd modes.

This arrangement is shown in Figure 8. In final and fourth option Option-4BRBs have been installed in cut in central core wall at bays 2 and 4 buckling restrained braces the location of maximum shear force in 2nd and 3rd modes in addition to the BRBs in Option This is shown in Figure 9.

Arrangement of the BRBs at locations of maximum racking shear deformation in exterior panels Option

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