Vol.38/No.3 (149) (2023)

steel panel damper, moment resisting frame, seismic design, optimization, software development, web service.

Incorporating a steel panel damper (SPD) into a moment resisting frame (MRF) can increase the stiffness, strength, and energy dissipation ability of the MRF. This research improves the previous optimization algorithm by using Sequential Least Squares Programming (SLSQP) nonlinear programming algorithm. The chosen algorithm takes less than one second to complete the optimization.Time-efficient algorithm has helped the authors to implement an optimization software into a web service to users. This paper demonstrates the optimization of single-cruciform (SC) and double-cruciform (DC) types of SPDs-to-beam subassemblies. Each SC or DC type has “Basic Design (BD)” and “1.5 times stiffened Design (1.5KD)” In the BD, the optimal depth of SPD in SC type is around 700~1200mm, while around 500~800mm in DC type. The optimal beam depth of SC type is around 700~1100mm, while around 600~800mm in DC type. The DC type can save up to 300 mm less beam depth than the SC type for a strong SPD of 1500kN nominal shear strength. Comparing the BD with the 1.5KD for both the SC and DC type subassemblies, the top three largest increases of dimensions are web thickness of elastic joint (EJ), boundary beam depth and web thickness. Applying a gravity load effect ratio 𝜉, it’s found that one can consider a ratio of 𝜉 up to 0.15 to consider the gravity load effect in the optimization without much additional cost. In the case of an 8-meter boundary beam with an SPD location eccentricity of 0.2 times the beam span, the induced SPD axial force would exceed 0.15 times of compression yield capacity of the EJ segment. It is recommended that the eccentricity be limited to less than 0.2 times the beam span. In the cases when boundary beam sizes are specified first, it is found that the DC type designs are more efficient in increasing structural stiffness than the SC type designs for the SPD-MRFs with long-span beams.

The main purpose of this study is to investigate the seismic performance of damped-outrigger system incorporating friction dampers through numerical analysis and shaking table tests. A 9 m tall steel structure specimen was designed by scaling down a 20-story benchmark model. The specimen was equally divided into ten floors and the outrigger beams together with the friction dampers can be installed in different floors. The normal force in the friction damper is adjustable so that its energy performance can be modified during the test. The seismic response of the specimen was evaluated by performing response spectral analysis (RSA) using the OpenSees numerical model. The equivalent damping ratio was included in the RSA in order to evaluate the energy dissipation resulted from the friction dampers. Based on the RSA results, the specimen configurations when outrigger locates at the sixth (6F), eighth (8F), and roof floors (RF) and when the normal force in the friction damper varies between 5 kN, 10 kN, and 20 kN were tested by imposing five different ground motions with the peak ground acceleration of 0.64g. Both the RSA and test results indicated that the maximum roof drift of the specimen was around 0.7% 0.4%, and 0.3% rad., when the outrigger locates at the RF, 8F, and 6F, respectively. The greater normal force applied in the friction damper generally result in a greater amount of energy dissipation and a smaller roof drift response. Based on the experimental and numerical results, the optimal design of the damped-outrigger system incorporating friction dampers are demonstrated in this study.

With the gradual increase in the demand for high-rise buildings, countries all over the world have developed high-strength concrete in order to reduce the size of components to reduce the weight of the structure and increase the usable space efficiently. The New RC project in Taiwan has also begun to promote the use of high-strength materials. It mainly conducts research on construction materials with concrete compressive strength (𝑓c′) above 70MPa and steel yield strength ( 𝑓y ) above 685MPa. However, as the compressive strength of the concrete material increases, its properties will gradually become brittle. Therefore, according to the current code, it is necessary to deploy a large amount of shear reinforcements in the stress interference area or the geometric discontinuity zone (D zone) such as beam-column joints. Stirrups are used to maintain the toughness and shear strength of the parts, but dense shear stirrups cause difficulties in reinforcement assembling during construction, and poor workability of concrete during casting, which results in the poor quality of concrete components. Adding steel fibers to high-strength concrete can delay brittle failure. Since the bridging effect between steel fibers can effectively inhibit the expansion of crack width, it can greatly reduce the configuration of transverse stirrups and solve construction problems.

According to the past experiments on the structural discontinuity area (D area), such as beam-column joints and deep beams, etc., the results show that the use of steel fibers in high-strength concrete can improve the toughness and shear strength of components, so the benefits of steel fiber reinforced concrete in structural discontinuities is known. This study carried out 4 high-strength steel fiber reinforced concrete shear wall experiments as the shear walls that are also members of the structural discontinuity area. The test parameters include the presence or absence of openings, the type of openings, the ratio of steel bars in the wall, the amount of stirrups in the boundary columns, and the configuration of reinforcement bars in the openings. Through the observation of the strength and deformation behavior of the test body and the development of cracks, the role played by steel fibers and the benefits of collocation with transverse reinforcement will be clarified in order to revise the prediction model and provide reference for future design.