A typical Buckling Restrained Brace (BRB) consists of a steel core and a mortar-filled tube to prevent buckling of the core. In BRBs, the mortar used in a casing considerably increases their weight. In another type of such braces, to reduce the weight, a steel casing is used to avoid buckling of the steel core. In this paper, discontinuous restraint is investigated analytically and numerically to manage buckling behavior of the core along the steel tube.

In the analytical section, equations are proposed to determine a suitable distance between the restraints in rectangular and cruciform sections using inelastic buckling, tangent and double modulus theories and their combination with the Romberg-Osgood behavioral model. In the numerical section, first the cyclic behavior of 9 Conventional BRB models with continuous and discontinuous mortar casing is evaluated using the Abaqus software. Then, the appropriate distance between restraints is determined for the numerical model and compared to those from analytical equations. Results show that the tangent modulus theory is more compatible with the finite element model. Moreover, in cruciform cores, it is possible to reduce the amount of mortar up to 64% without any changes in the cyclic behavior of bracing. Finally, two all-steel BRB models are exposed to cyclic loading where steel plates prevent core bucking. Those results demonstrate that the cumulative ductility exceeds the minimum value defined by AISC.

典型的屈曲约束支撑（BRB）由钢芯和防止砂芯屈曲的砂浆填充管组成。在BRB中，套管中使用的砂浆会大大增加其重量。在另一种此类支架中，为了减轻重量，使用钢制外壳来避免钢芯弯曲。在本文中，对不连续约束进行了分析和数值研究，以管理铁心沿钢管的屈曲行为。

在分析部分中，使用非弹性屈曲，切线和双模量理论及其与Romberg-Osgood行为模型的组合，提出了确定矩形和十字形截面约束之间的合适距离的方程。在数字部分，首先使用Abaqus软件评估9个带有连续和不连续砂浆套管的常规BRB模型的循环行为。然后，为数值模型确定约束之间的适当距离，并将其与解析方程式中的约束进行比较。结果表明，切线模量理论与有限元模型更加兼容。而且，在十字形芯中，可以将砂浆的用量减少多达64％，而不会改变支撑的循环行为。最后，两种全钢BRB模型承受周期性载荷，在这种载荷下钢板可防止铁芯弯曲。这些结果表明，累积延展性超过AISC定义的最小值。