Comparative seismic performance analysis of steel braced frames with resilient slip-friction joint braces and buckling-restrained braces

Influence of BRBs deformation capacity on the seismic performance of RC building frames

Seismic performance analysis of multi-story steel frames equipped with FeSMA BRBs

As a new type of energy dissipation component with excellent mechanical performance, the Buckling-Retrained Braces (BRBs) were gradually applied in retrofitting and improving seismic performance of reinforced concrete structures in China. In order to investigate the seismic performance of reinforced concrete structures retrofitted with BRBs, quasi-static test of two single-bay and 3-story reinforced concrete frames specimens was conducted and introduced in this paper. Two 1/2 scaled specimens were designed to reflect real prototype structure. For comparison, one control specimen was designed without BRBs, and the other specimen was retrofitted with BRBs. And particularly, for the specimen retrofitted with BRBs, the BRBs were eccentric layout instead of usually concentric or x-shaped layout, aiming to be more suitable for large-span frames. In the test, the failure mode, carrying capacity, deformability, ductility and energy dissipation ability of both two specimens were investigated. Based on the test results of the measured hysterical curves, skeleton curves, the seismic performances such as bearing capacity, plastic deformability, energy dissipation ability and ductility of two specimens were fully studied. And from the test results, it was indicated that the specimen retrofitted with BRBs showed much better seismic performance than the control specimen without BRBs, and the BRBs could effectively improve the seismic performance of the reinforced concrete frame. For the specimen retrofitted with BRBs, the BRBs firstly yielded before the beam-ends and the column-ends, and an expected yielding process or yielding mechanism as well as good seismic performance was obtained. For the specimens without BRBs, though the beam-ends yielded prior to the column-ends, the seismic performance was much poor than that of the specimen with BRBs.

In highway expansion and reconstruction projects, existing slopes often lead to significant variations in pier heights, forming Irregular Slab-Column Bridge Structures (ISCB). When subjected to seismic loading, such structures exhibit complex mechanical behavior, thereby highlighting the necessity of seismic mitigation design. This study is based on an irregular double-column slab-column highway bridge structure (with a short column of 3 m and high columns of 4 to 9 m) and conducts seismic response analysis using a finite element model. Subsequently, buckling-restrained braces (BRBs) were introduced to evaluate the influence of BRB force ratio on seismic mitigation performance. On this basis, an optimization design method was proposed based on the relationship between the BRB stiffness factor and force ratio. By adjusting the ratio between the BRB force ratio and the computed BRB stiffness factor KF, optimal seismic mitigation and self-centering performance of the structure can be achieved under earthquake loading. This approach effectively prevents local over-deformation and unbalanced responses, enhancing overall seismic performance. The results indicate that the short column exhibits a larger seismic response. When the short column is 3 m and the high column is 6 m, the disparity in seismic responses between the two columns tends to diminish with increasing high column height. The incorporation of BRBs can significantly reduce the structural base shear, reinforcement strain at the column base, and displacement at the column top. Moreover, the reduction in seismic response becomes more pronounced with increasing BRB force ratio. The proposed optimization design method takes into account both the seismic mitigation performance of the BRBs and the self-centering capability of the ISCB. Using this method, the optimal BRB design parameters for the example ISCB are determined (FRBRB=0.3, KF = 3.3). The proposed method for integrating BRB components into bridge pier design can significantly enhance the seismic performance of the prototype structure, promote rapid functional recovery following strong earthquakes, and serve as a novel strategy for the seismic mitigation design of ISCB structures.

This study involves the application of timber‐based bracings elements. For this purpose, seismic analyses are performed on special portal steel frames without the brace and diagonally braced with Glued Laminated Timber (glulam) and Timber‐Steel Buckling Restrained Brace (TS‐BRB), and the results are compared with the same configuration using steel Hollow Structural Sections (HSS) bracing, using OpenSees structural analyzer. First, to verify the accuracy of the modeling, the numerical results are compared with experimental measurements on several types of elements: (a) diagonally braced frame with steel Hollow Structural Sections with a concentrically steel braced frame which was tested by the quasi‐static method under cyclic loading protocol by previous researchers, (b) diagonally glulam braced frame with results of shake table tests on single‐story timber braced frames, and (c) Timber‐Steel Buckling Restrained Brace (TS‐BRB) frame with experimental results of Heavy Timber Buckling‐Restrained Braced Frame (HT‐BRB). In the second step, the aforementioned timber base bracing alternatives (glulam, TS‐BRB) are applied in the special portal steel frame, then the seismic performance of the frame is investigated under pushover, cyclic, time history, and incremental dynamic analysis (IDA), and then the results are compared with the behavior of similar portal frame in two conditions without the brace and diagonally braced with the steel‐HSS brace. Results showed that steel‐HSS, glulam, and timber‐steel buckling restrained braces have significant roles in energy dissipation, increasing shear capacity, decreasing interstory drift, and decreasing weight and cost of estimation of the structure.

Buckling-restrained braces (BRBs) are widely adopted for seismic retrofitting, yet the performance trade-offs between stiffness and ductility in high-rise reinforced concrete (RC) frames under region-specific seismic conditions remain underexplored. This study investigates the seismic performance of a 10-story, 5-bay reinforced concrete (RC) frame, comply with Indonesian standards SNI 1726:2019 and SNI 2847:2019 (ASCE 7-16 and ACI 318-14), retrofitted with two distinct buckling-restrained brace (BRB) configurations: (1) BRB with large initial stiffness but less ductility and (2) BRB with low initial stiffness but enhanced ductility. A 2D nonlinear model of the RC frame was developed, featuring 3 m inter-story heights and 6 m span bays. Beam-column elements were modeled as line elements with nonlinear shear and bending springs, while BRBs were represented using a bi-linear hysteresis model. Two BRBs were installed in bays 2 and 4, targeting stories with elevated inter-story drift. Eleven spectrum-matched ground motions were scaled to Indonesian geographical conditions to evaluate seismic responses. Key performance metrics included inter-story drift response and BRB force-displacement behavior. Results demonstrated that BRB with strong initial stiffness effectively reduces peak inter-story displacement compared to BRB with weak stiffness. However, BRB with weak stiffness achieves greater cumulative ductility. Both types of BRB still reduce structural damage but have their unique characteristics. The study uniquely quantifies the stiffness-ductility trade-off in high-rises, demonstrating that strong-stiffness BRBs prioritize immediate drift control, while weak-stiffness BRBs enhance post-yield stability. Keywords: Seismic performance, reinforced concrete building, parametric study, buckling-restrained brace

ABSTRACTA novel implementation of buckling‐restrained braces (BRB) in new reinforced concrete (RC) frame construction is investigated. Seismic design and analysis methods for the use of the proposed steel cast‐in anchor bracket (CAB) as the connection for the BRB and RC members are investigated. The steel CAB is designed to resist the normal and shear forces transferred from the BRB in order to secure the seismic performance of RC buildings. In this study, a full‐scale two‐story RC frame with BRBs (BRB‐RCF) is tested using hybrid and cyclic loading test procedures. The BRBs are arranged in a zigzag configuration and designed to resist 70% of the story shear. The gusset design incorporates the BRB axial and RC frame actions, while the beam and column members comply with ACI 318‐14 seismic design provisions. When the inter‐story drift ratio for both stories reached 3.5%, the overall lateral force versus deformation response was still very stable. The hysteresis energy dissipation ratios in the four hybrid tests range from 60% to 94% in the two stories, indicating that BRBs can effectively dissipate seismic input energy. Test results confirm that BRBs enhanced the RC frame stiffness, strength and ductility, complied with performance‐based seismic design. No failure of the proposed steel CABs and RC discontinuity regions was observed in the tests. This study demonstrates that the proposed design and construction methods for the CABs are effective and practical for real applications.

The properly constructed buckling restrained braces (BRBs) usually have good ductility and energy dissipation capacity and therefore can be used in braced steel frames. However, large residual plastic deformation of the BRBs deteriorates their resilience capacity and hence results in large residual deformation of the buckling restrained braced steel frames (BRBFs) under large drifts. To reduce the residual deformation of BRB while keeping good ductility and energy dissipation capacity, a new self-centering buckling restrained brace (SCBRB), letting both BRB part and self-centering part work in parallel, is proposed. The self-centering capacity of SCBRB is provided by a combination of pre-compressed disc springs, which provides restoring forces and facilitates reduction of the residual deformation of the BRB. The BRB is composed of a core steel plate brace, a restraining member formed by the circular steel tube filled with mortar, and debonding materials between them. By quasi-static tests, one self-centering buckling restrained brace specimen (SCBRB) and one pure BRB specimen were tested to mainly examine the constructional details and hysteretic behavior of SCBRB. The material and configuration details of core steel plate brace in both the SCBRB and the pure BRB are the same for comparison. The test results show that, compared with the pure BRB which still exhibits large residual deformation, the SCBRB presents a flag-shape hysteretic performance and its residual deformation decreases significantly. The hysteretic curves of both the SCBRB and the pure BRB are stable before tension fracture of plate brace due to low cyclic fatigue, and the other components remained intact.

Improving the seismic performance of diagrid structures using buckling restrained braces

Seismic design and performance of dual structures with BRBs and semi-rigid connections

Buckling-restrained braces have adequate seismic performance characteristics such as high energy absorption due to their symmetric behaviour in compression and tension. However, low post-yield stiffness is one of the main disadvantages of these braces. The stiffness values of buckling-restrained brace frames can highly degrade when the core segments are yielded. Reducing the length of the yielding segments of buckling-restrained braces is being proposed and investigated by many researchers, considering the high strain capacity of steel in the post-elastic region. This article focuses on a type of buckling-restrained brace called reduced yielding segment buckling restrained brace or in short, ‘reduced length buckling restrained brace’. In such frames, the length of the yielding part is reduced and placed in one end of the brace element. In this research, the seismic performances of the above-mentioned buckling-restrained braces were investigated through probabilistic approach and compared with those of conventional buckling-restrained braces. Their performances were quantitatively assessed in terms of two limit states, immediate occupancy and collapse prevention. The fragility curves, the mean annual limit states frequencies and the seismic demand hazard curves of the frames were plotted using probabilistic seismic demand analysis. According to the results obtained for immediate occupancy limit state, the frames braced with reduced length buckling restrained braces show better seismic performances compared to those braced with conventional buckling-restrained braces. However, for collapse prevention limit state, it is hard to comment accurately because in some cases, reduced length buckling restrained braced frames show enhanced seismic performance while in other cases, conventional ones exhibit improved response.

In this paper, a double-stage yield buckling restrained brace (DYB) is proposed to prevent soft story collapse in structures subjected to strong earthquakes. The DYB consists of two conventional buckling restrained braces (BRBs) with different yield forces: a large BRB and a small BRB. The deformation of the small BRB has an upper threshold value, controlled by a special mechanical mechanism. Once the force acting on the DYB exceeds the yield force of the small BRB, the small BRB yields and the deformation concentrates on the small BRB. When the deformation of the small BRB reaches the threshold value, the small BRB stops deforming. If the force of the DYB continues to increase and exceeds the yield force of the large BRB, the large BRB yields and most of the deformation takes place in the large BRB. In this way, the DYB achieves a double-stage yield mechanism. To demonstrate the effectiveness of the DYB, a model of a six-story reinforced concrete frame equipped with DYBs was constructed using the finite element software ABAQUS, and its seismic performance was analyzed. The double-stage yield mechanism of the DYB was simulated by a gap element. To investigate the effect of DYBs on the seismic performance of the structure, four different models were built: an unbraced frame, frame with DYB, frame with small BRB, and frame with large BRB. The results of the pushover and time-series analyses showed that the DYB effectively controlled the deformation pattern of the structures, and prevented weak story collapse.

Development and validation analysis of a steel-lead hybrid dual-yield BRB for multi-stage seismic energy dissipation

Cyclic loading test of double K-braced reinforced concrete frame subassemblies with buckling restrained braces

The conventional brace appears buckling easily under the strong earthquake. and it can not meet the demand of the structure. The hysteretic behavior is stable and the energy absorption capacity is good. The buckling — restrained brace (BRB) can undergo fully reversed axial yield cycles without loss of stiffness and strength. Ocean platform structure is complicated, and the surrounding environment is harsh. It is significant to study the platform structure vibration control. BRB structure with isolation layer under earthquake and ice load simulation is studied based on ANSYS. The results show that the BRB can reduce the seismic responses of the ocean platform and significantly suppress the maximal acceleration by dissipating the vibration energy through inelastic deformation. The seismic performance is improved. Therefore BRB with simlpe bilinear resilisence is adoptadopted in structure wiih more reqirment to resist horizontal and seismic load. It has a good future.