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Ocak, Ayla; Bekdaş, Gebrail; Nigdeli, Sinan Melih
doi: 10.1002/tal.1907pmid: N/A
This study focuses on the optimization of tuned liquid dampers (TLDs) by using metaheuristic methods using a natural phenomenon as inspiration. Unlike tuned mass dampers (TMDs), TLDs consist of two parts of bodies that contain the passive liquid that is stationary and the active part of the liquid that involves in sloshing. To optimize the amount of optimum active and passive liquids by finding the best dimensional properties of the liquid tank, a two‐degree‐of‐freedom (DOF) model was used as TLD in the dynamic analysis used in the optimization that aims to reduce the maximum displacement of the structure under earthquake excitations. For this purpose, water, oil, and glycerin liquids were selected for TLD. TLD parameters were optimized with the help of Jaya algorithm, flower pollination algorithm (FPA), harmony search (HS) algorithm, and teaching–learning‐based optimization (TLBO). Total acceleration and maximum displacement were evaluated after optimization. The performance of TLD under earthquake excitations has been also compared with TMDs. According to the results, the optimized TLD has a better performance than TMD, and Jaya algorithm has a slightly better performance than the other algorithms.
Qin, Jiangui; Wang, Zhan; Pan, Jianrong; Li, Bin; Fan, Yanjing
doi: 10.1002/tal.1906pmid: N/A
Due to recent advances in computational power, high efficiency and high precision semi‐rigid calculation methods of steel connections are necessary. In this paper, four connection experiments were designed to study the mechanical behavior of the top and seat angle connections. In the experiment, a monotonic load was applied at the end of the beam to study its moment–rotation characteristics. In addition, this paper proposed a second derivative method to determine the yield point, the starting point of the plastic strengthening stage, and the initial rotational stiffness of the connections according to the moment–rotation curve. Loading test experiments (EX) results and finite element analysis (FEA) results showed that the compression side angle stiffener has little effect on the initial rotational stiffness. Nevertheless, it can delay the top and seat angle connection in entering the elastoplastic stage and the starting point of the plastic strengthening stage. The results also showed that the tension side angle stiffener could significantly increase the initial rotational stiffness, but makes the angle connection enter the yield stage earlier. When the connection's top and seat angles have no stiffener, the elastoplastic deformation range on the curve is smaller. Finally, based on the theory of Plates and Shells, this paper proposed the calculation method for the deformation stiffness of the key components and the initial rotational stiffness of the connection. Results from the theoretical calculation method showed high calculation accuracy and high calculation efficiency, as compared with the EX and the FEA results.
Sotiropoulos, Stefanos; Lagaros, Nikos D.
doi: 10.1002/tal.1909pmid: N/A
In this work, a combined ground structure topology–sizing optimization‐based methodology is presented, for supporting the design phases of moment‐resisting braced frames (MRBFs) for tall buildings, from the conceptual design phase to the final one. The mathematical problem is formulated as a minimum material volume problem subject to compliance and design check constraints imposed by the serviceability and ultimate limit states of the Eurocode design provisions, while the optimized designs achieved are composed of standardized section properties of the Euronorm. Most of the studies that rely on ground structure topology optimization formulation are limited to truss structures, while compliance is used as the objective to be minimized. Considering structural systems composed of elements that develop both axial and flexural stress, together with topology optimization problem formulation where the material volume is to be minimized, describe the major challenges of this study. The minimum material volume problem initially is dealt with by a frame structural topology optimization (FSTO) approach representing the conceptual design phase followed by a sizing structural design optimization procedure referring to the final design phase. In order to test the efficiency of the methodology, it is implemented for designing the structural system of MRBFs for mid‐ and high‐rise building structures. For the case of the real‐world structural systems examined, a variant of the methodology is used where its second design phase is implemented by means of the optimization computing platform (OCP) integrated with the commercial software ETABS v18.
Lu, Hongna; Zhang, Huagang; Ma, Kejian; Li, Li; Chen, Hongniao; Wu, Qin; Jiang, Lan
doi: 10.1002/tal.1905pmid: N/A
A reinforced concrete vierendeel beam (RCVB) is an open‐web structure formed by connecting the top and bottom chords through block‐shaped shear keys. In this study, the static load test was applied to understand the failure state and reinforcement ratios relationship with bending capacity of RCVBs. The results reveal that numbers of horizontal cracks appeared in the chord‐key node area of the bending‐shear section. The deflection development of specimens experienced elastic, elastic–plastic, and plastic stages. The failure of the beam was controlled by the deflection and the ultimate load increased with the reinforcement ratio. A combined model for calculating the bending capacity of the top chords under eccentric compression and the bottom chords under axial tension is proposed. With the measured strains the loading coefficient of the beams are 1.15–1.20. According to the Chinese code, the continuous loading after the longitudinal reinforcement of the bottom chord yielding can make the top chord concrete reach the ultimate compressive strain, and the loading coefficient of the beams are 1.1–1.2. Therefore, the proposed model and formulas can effectively calculate the flexural bearing capacity of RCVBs. The finite element analysis results further indicate that the proposed calculation model and algorithm are appropriate.
Yin, Fei; Wang, Ruwei; Cao, Wanlin; Dong, Hongying; Zhao, Yang; Song, Yu
doi: 10.1002/tal.1908pmid: N/A
To study the seismic behavior of steel reinforced concrete columns with various cross‐sectional shapes, steel shapes, and concrete strengths, four large‐size specimens were designed and an experimental study was conducted. High‐strength concrete can effectively improve the bearing capacity, stiffness, and energy dissipation capacity of proposed specimens, while the specimens with high‐strength concrete showed more serious compressive damage and lower ductility index. The square specimens showed more significant bearing capacity decline after the peak point than rectangular specimens and the ductility indexes were smaller. However, the ductility indexes and peak drift ratios of all specimens were larger than 3.58 and 1/50, which still met the suggested values in the related code. The ductility indexes and residual deformations of square specimens with high‐ and low‐strength concrete were more closed than those of rectangular specimens with high‐ and low‐strength concrete, indicating that the proposed square specimens had more stable deformation capacity under different concrete strength. Furthermore, considering the different confinement effects of concrete in different regions, the stress–strain relationships of concrete in different regions were calculated individually and a modified fiber‐based method was proposed. The calculated results showed good agreement with the experimental results, indicating that the method can be used for the design of steel reinforced concrete column cross‐sections.
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