• Computers and Concrete
• /
• v.2 no.2
• /
• pp.147-164
• /
• 2005

This paper summarizes an experimental study on the seismic behavior of lower stories of a mid-rise reinforced concrete frame building. Two reinforced concrete frames with two stories and one span were tested and each frame represents lower two stories of an 11-story RC frame building. Both frames were designed in accordance with Japanese design guidelines and were identical except in the variation of axial force. The tests demonstrated that the overall load-displacement relations of the two frames were nearly the same and the first-story column shear was closely related to the column axial load. The columns and beams elongated during both of the tests, with the second-floor beam elongation exceeding 1.5% of the beam clear span length. The frame with higher axial loads developed more cracks that the frame under moderate axial load.

• Structural Engineering and Mechanics
• /
• v.60 no.2
• /
• pp.251-269
• /
• 2016

In common structural systems, there are some limitations to provide adequate lateral stiffness, high ductility, and architectural openings simultaneously. Consequently, the concept of T-Resisting Frame (TRF) has been introduced to improve the performance of structures. In this study, Configuration of TRF is a Vertical I-shaped Plate Girder (V.P.G) which is placed in the middle of the span and connected to side columns by two Horizontal Plate Girders (H.P.Gs) at each story level. System performance is improved by utilizing rigid connections in link beams (H.P.Gs). Plastic deformation leads to tension field action in H.P.Gs and causes energy dissipation in TRF; therefore, V.P.G. High plastic deformation in web of TRF's members affects the ductility of system. Moreover, in order to prevent shear buckling in web of TRF's members and improve overall performance of the system, appropriate criteria for placement of web stiffeners are presented in this study. In addition, an experimental study is conducted by applying cyclic loading and using finite element models. As a result, hysteresis curves indicate adequate lateral stiffness, stable hysteretic behavior, and high ductility factor of 6.73.

• Structural Engineering and Mechanics
• /
• v.78 no.3
• /
• pp.269-280
• /
• 2021

Reinforced concrete (RC) structural walls with L-shaped sections are commonly used in RC buildings. The walls are often expected to sustain biaxial load and Unsymmetrical bending in an earthquake event. However, there currently exists limited experimental evidence regarding their seismic behaviour in these lateral loading directions. This paper makes experimental and numerical investigations to these walls behaviours. Experimental evidences are presented for four L-shaped wall specimens which were tested under simulated seismic load from different lateral directions. The results highlighted some distinct behaviour of L-shaped walls sustaining Unsymmetrical bending relating to their seismic performance. First, due to the Unsymmetrical bending, out-of-plane reaction forces occur for these walls, which contribute to accumulation of the out-of-plane deformations of the wall, especially when out-of-plane stiffness of the section is reduced by horizontal cracks in the cyclic load. Secondly, cracking was found to affect shear centre of the specimens loaded in the Unsymmetrical bending direction. The shear centre of these specimens distinctly differs in the flange in the positive and negative loading direction. Cracking of the flange also causes significant warping in the bottom part of the wall, which eventually lead to out-of-plane buckling failure.

• Journal of Korean Society of Steel Construction
• /
• v.16 no.6 s.73
• /
• pp.781-792
• /
• 2004

Experiments were performed to study the cyclic behavior of framed steel walls with thin web plates. Five specimens of single-bay and three-story steel plate walls were tested for cyclic lateral load. The parameters for the test specimens included the plate thickness and the column strength. Based on the test results, the strength, deformability, and energy dissipation capacity of the framed steel walls were studied. The test results showed that the behavioral characteristics of the framed steel walls with thin web plates were different in many aspects from those of the conventional braced frame, and the steel wall with a stiffened web plate exhibited cantilever action, high strength, and low ductility. With the framed steel plate walls, local plate buckling and tension-field action developed in the thin web plates, and plastic deformation was uniformly distributed along the wall's height. As a result, the framed steel plate walls exhibited combined flexural and shear deformation, but they also showed high strength and energy dissipation capacity. Moreover, such walls have high deformability, which was equivalent to that of the conventional moment frame. Frame members such as columns and beams, however, must be designed to resist the tension-field action of the thin web plates. If the column does not have sufficient strength, and if its sections are not compact enough, the overall strength of the framed steel wall might be significantly decreased by the development of the soft-story mechanism. The framed steel walls with thin web plates have advantages, such as high deformability and high strength. Therefore, they can be used as ductile elements in earthquake-resistant systems.

• Earthquakes and Structures
• /
• v.24 no.5
• /
• pp.317-331
• /
• 2023

The buckling-restrained braced frames with eccentric configurations (BRBFECs) are stable cyclic behavior and high energy absorption capacity. Furthermore, they have an architectural advantage for creating openings like eccentrically braced frames (EBFs). In the present study, it has been suggested to use the performance-based plastic design (PBPD) method to calculate the design base shear of the BRBFEC systems. Moreover, in this study, to reduce the required steel material, it has been suggested to use the performance-based practical design (PBPD) method instead of the force-based design (FBD) method for the design of this system. The 3-, 6-, and 9-story buildings with the BRBFEC system were designed, and the finite element models were modeled. The seismic performance of the models was investigated using two suits of ground motions representing the maximum considered earthquake (MCE) and design basis earthquake (DBE) seismic hazard levels. The results showed that the models designed with the suggested method, which had lower weights compared to those designed with the FBD method, had a desirable seismic performance in terms of maximum story drift and ductility demand under earthquakes at both MCE and DBE seismic hazard levels. This suggests that the steel weights of the structures designed with the PBPD method are about 13% to 18% lesser than the FBD method. However, the residual drifts in these models were higher than those in the models designed with the FBD method. Also, in earthquakes at the DBE hazard level, the residual drifts in all models except the PBPD-6s and PBPD-9s models were less than the allowable reparability limit.

• Journal of Korean Society of Steel Construction
• /
• v.12 no.4 s.47
• /
• pp.351-362
• /
• 2000

This paper is to study on the behavior of CFT column to H-beam end plate connections with penetrated high-strength bolts under cyclic load. The main parameters are as follows: 1) the thickness of end plate: 16mm, 22mm and 25mm, 2) the thickness of column : 9mm and 12mm. Comparison and analysis on the test results are performed in accordance with parameters. This study investigates energy absorption capacity of beam-column connections and analyzes the shear strength of joint panel. The shear strength of joint panel is estimated by superimposing the strength of the steel which is based on the von Mises yield criterion and that of the concrete which is used the Strut model to consider the effect of filled concrete.

• Structural Monitoring and Maintenance
• /
• v.5 no.2
• /
• pp.205-229
• /
• 2018

Energy induced by minor earthquake and micro vibration cannot be dissipated by traditional buckling-restrained braces (BRBs). To solve this problem, a new type of hybrid passive control device, named as VE-BRB, which is configured by a BRB with high-damping viscoelastic (VE) layers, is developed and studied. Theoretical analysis, performance tests, numerical simulation and case analysis are conducted to study the seismic behavior of VE-BRBs. The results indicate that the combination of hysteretic and damping devices lead to a multi-phased nature and good performance. VE-BRB's working state can be divided into three phases: before yielding of the steel core, VE layers provide sufficient damping ratio to mitigate minor vibrations; after yielding of the steel core, the steel's hysteretic deformations provide supplemental dissipative capacity for structures; after rupture of the steel core, VE layers are still able to work normally and provide multiple security assurance for structures. The simulation results agreed well with the experimental results, validating the finite element analysis method, constitutive models and the identified parameters. The comparison of the time history analysis on a 6-story frame with VE-BRBs and BRBs verified the advantages of VE-BRB for seismic protection of structures compared with traditional BRB. In general, VE-BRB had the potential to provide better control effect on structural displacement and shear in all stages than BRB as expected.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.3
• /
• pp.84-91
• /
• 2022

In this study, an experimental study was conducted to analyze the hysteresis behavior according to the steel fiber aspect ratio and volume fraction of diagonally reinforced concrete coupling beams under to cyclic loading. The aspect ratio and volume fraction of the steel fibers were set as the main variables, and 4 specimens were fabricated in which the amount of transverse reinforcement of the coupling beam suggested in the domestic building structural standard was relaxed by about 53%. In the experiment, cyclic loading experiments were performed in the displacement control method in accordance with ACI 374.2R-13, and as a result of the experiment, it was found that all specimens containing steel fibers exceeded the nominal shear strength suggested by the current structural standards. As the aspect ratio of the steel fibers increased, the steel fibers prevented the buckling of the diagonal reinforcement, and the bridging effect of the steel fibers held the crack surface of the concrete. The shear strength, stiffness reduction and energy dissipation capacity of the specimens containing steel fibers were superior to those of the Vf0 specimens without steel fibers. Therefore, it is judged that the steel fiber reinforced concrete can relieve the details of the transverse reinforced.

• Journal of Korean Society of Steel Construction
• /
• v.14 no.4
• /
• pp.499-508
• /
• 2002

A simple design method for rib-reinforced seismic steel moment connections has been recently proposed based on the equivalent strut model. An experimental program was implemented to verify the proposed design method, as well as develop the schemes that will prevent cracking at the rib tip where stress concentration was evident. All specimens designed using the proposed method were able to develop a satisfactory connection plastic rotation of 0.04 radian. In addition to rib reinforcement, slight beam flange trimming pushed the plastic hinging and local buckling of the beam away from the rip tip and effectively reduced cracking potential at the rib tip. Using strain gage readings, the strut action of the rib and resulting reverse shear in the beam web were also experimentally identified.

• Steel and Composite Structures
• /
• v.34 no.1
• /
• pp.107-122
• /
• 2020

Moment resisting stub columns (MRSCs) have increasingly adopted in special moment-resisting frame (SMF) systems in steel building structures, especially in Asian countries. The MRSCs typically provide a lower deformation capacity compared to shear-panel stub columns, a limited post-yield stiffness, and severe strength degradation as adopting slender webs. A new MRSC design with cored configuration, consisting of a core-segment and two side-segments using different steel grades, has been proposed in the study to improve the demerits mentioned above. Several full-scale components of the cored MRSC were experimentally investigated focusing on the hysteretic performance of plastic hinges at the ends. The effects of the depths of the core-segment and the adopted reduced column section details on the hysteretic behavior of the components were examined. The measured hysteretic responses verified that the cored MRSC enabled to provide early yielding, great ductility and energy dissipation, enhanced post-yield stiffness and limited strength degradation due to local buckling of flanges. A parametric study upon the dimensions of the cored MRSC was then conducted using numerical discrete model validated by the measured responses. Finally, a set of model equations were established based on the results of the parametric analysis to accurately estimate strength backbone curves of the cored MRSCs under increasing-amplitude cyclic loadings.