Explore the vast range of titles available.

Summary As a low cost and maintenance energy‐absorbing device, tuned liquid damper (TLD) is being widely used to suppress structural vibration. In this paper, the real‐time hybrid simulation (RTHS) is employed to investigate the performance of TLD for controlling seismic responses of actual multi‐story structures, where the TLD is experimentally modeled as physical substructure and the multi‐story structure is numerically simulated as numerical substructure. Taking advantage of RTHS technique, a methodology for achieving full‐scale TLD experiments is developed through suitable similarity design; a new interaction force measurement method and a new dual explicit algorithm are embedded into RTHS system to enhance simulation capability. First, the seismic response of a two‐story structure installed with TLD is analyzed by applying RTHS. Correspondingly, the pure shaking table test is performed to assess the accuracy of the RTHS. Then, the effectiveness of TLD for structures with various numbers of floors and different structural properties is tested through RTHS by varying the simulation model of the numerical substructure. Finally, the effects of mass ratio and structural damping ratio on a given TLD‐structure system are investigated. Copyright © 2015 John Wiley & Sons, Ltd.

In this study, we propose a structural health monitoring and diagnostic method for layered (multi-story) structures using a convolutional neural network (CNN). The proposed method is a primary diagnostic one, and its purpose is to allow quick identification of the location of an abnormality after detecting it. An abnormality is defined as a decrease in the stiffness characteristics (spring constant) of the outer wall of a multi-story structure when it deteriorates or is damaged. The proposed method has the following features. A modal circle is generated by multiplying the frequency response functions (FRFs) simulated by a mathematical model and the FRFs from the actual structure, in frequency space, and then a CNN learns the features of the abnormality from the modal circle and diagnoses it in the actual multi-story structure. We first verified the validity of the proposed method by considering a three-story structure as a numerical example. When the method was applied to three types of abnormal conditions, it was shown that the abnormal diagnosis could be performed correctly. Next, we constructed an experimental model of a three-story structure, and realized three types of abnormal conditions similar to those in the numerical model. We verified the applicability of the proposed method and showed that correct diagnosis of an abnormality was possible. Both the validity and applicability of the proposed method were thus confirmed.

Joint damage initiates a consequential form of damage in the beam-to-column connection in a steel frame structure. Many traditional damage detection techniques are not suited for such cases. However, available vibration-based methods are unable to provide a general joint damage detection technique that can be applied to all types of structures. The primary objective of this study is to develop a connection damage identification technique for a 3D frame using a convolutional neural network (CNN) model. For that purpose, a five-story steel 3D frame is considered. An impact hammer is utilized to excite the structure and collect acceleration responses at various points under both undamaged and damaged conditions. From these responses, scalogram images are generated, which serve as input for the CNN-based deep learning technique. The results are then compared with those obtained using the AlexNet model. The training and testing results demonstrate that the technique can effectively differentiate between undamaged and damaged classes, showcasing its potential as an automated tool for the health monitoring of frame connections. The robustness of the technique is further computationally verified through environmental variability, along with the localization and severity of the damage.

In a moderate seismic activity, relying solely on the static force method to estimate the seismic force assessing the vulnerability and behaviour of RCC buildings under seismic loads is insufficient. The seismic response of the building system is highly influenced by the analysis method adopted. In the past years, static approaches were preferred due to their simplicity, although these methods provided safe design, they may have been overly cautious. Dynamic analysis, on the other hand, is a fundamental aspect of structural mechanics, that describes and predicts the behaviour of structures subjected to dynamic loads. Dynamic load includes wind, imposed load, earthquake, etc. Dynamic analysis techniques, such as modal analysis, time history analysis, and dynamic displacement analysis. RCC structures are mainly designed to resist static load. This process of ignoring dynamic events sometimes becomes the cause of disasters, especially in the case of earthquakes. This research paper provides information on the comparison of various parameters in static and dynamic analysis. Two RCC multistoried residential buildings (g+10 and g+25) acting on seismic zone IV are analyzed using the static analysis method and response spectrum method with ETABS 16. The research investigates the effect on various structural parameters such as story displacement, story drift, and support reactions. The results are compared and evaluated to assess the performance of the response spectrum method over the static analysis method.

PEC column has a wide prospect for strengthening existing steel structure buildings because of their high strength, stiffness, and bearing capacity. The seismic performance of the original steel structure could be significantly improved by filling the trough of section steel with concrete to form a partially encased composite column. Especially for multi-story buildings, the PEC column is an ideal edge restriction structural element, so it is of great significance to study its seismic performance. PEC column was introduced into steel frame structure, and six models of 8-story steel frame structures with PEC columns were established by using OpenSees finite element software. The displacement load curve, the maximum axial force in the column, the maximum bending moment at the column base, and the maximum inter-story shear force were obtained by Pushover analysis. The influence of concrete grade and the width-thickness ratio of the steel sheet of the PEC column on the mechanical properties of the whole structure was studied. Results show that lateral stiffness, ductility, and shear load-bearing capacity of the structure are improved with the addition of concrete in section steel, but ductility of the structure decreases with an increase of concrete strength grade. The influence of variation of PEC column parameters on the bottom of the structure is better than that on top. The width-thickness ratio of the section steel flange plays a major role in controlling the mechanical properties of the structure. The elastic stiffness of the structure, axial force of the column, and bending moment of the column base increase with the increase of flange thickness as section height is the same. An increase of the width-thickness ratio of the flange can improve the shear force of the story, and the lower the number of stories, the more significant the effect is.

This paper presents vibration control responses of a multi-story structure installed with a semi-active magneto-rheological(MR) damper. As a first step, performance characteristics of three different working modes for MR fluid are compared and the mixed mode type of MR damper is chosen as an optimal candidate for the vibration control of the multi-story structure. An appropriate size of the mixed mode MR damper is devised and manufactured on the basis of the field-dependent Bingham model of the MR fluid which is commercially available. The damping force of the mixed mode MR damper is evaluated with respect to the excitation frequency at various magnetic fields. After formulating the governing equation of motion for the small scaled three-story structure associated with the MR damper, the linear quadratic regulator(LQR) controller to effectively suppress unwanted structural vibrations is designed by imposing semi-active actuating conditions. The control algorithm is then empirically implemented under earthquake conditions and the control responses of the horizontal relative displacement and acceleration are evaluated in time and frequency domains through computer simulations.

In situ dynamic tests were conducted on Caiyunjian Tower to investigate the influence of a high stylobate on its dynamic characteristics and seismic response through time–domain and frequency–domain methods. Finite element models were developed for Caiyunjian Tower (wooden structure and platform) and the overall structure including the high stylobate. Subsequently, models were subjected to El Centro, Taft, and Lanzhou waves at varying amplitudes. The seismic response results indicate that the overall structure model exhibits a low natural vibration frequency with closely spaced modal frequencies. As the peak seismic wave acceleration increases, both models exhibit increased acceleration, displacement, and shear responses. The Caiyunjian Tower model shows greater sensitivity to the El Centro wave, whereas the overall structure model is more responsive to the Taft wave. Under seismic waves with identical peak acceleration, the overall structure model exhibits greater dynamic responses than the Caiyunjian Tower model. The high stylobate minimally affects the lower-order frequencies of the upper structure but significantly influences the higher-order frequencies. Therefore, the high stylobate has an adverse influence on the seismic behavior of Caiyunjian Tower.

Bottom-business multi-story masonry structure is widely used in small and middle towns in the southward in China. In the downtown of Beichuan county which affected by Wenchuan earthquake, more than 80% of this kind of building collapsed. But the Apartment of Beichuan Telecommunication Bureau behaved well earthquake resistant capacity with a moderate damage in the earthquake. The obvious difference between this building and others is the setting of winged columns in the front longitudinal wall of the first floor. For proving the influence of these members in the structure seismic capacity, the earthquake simulation shaking table test of 2 1/5 reduced scale models were designed and carried out. The models dynamic response, acceleration, displacement and strain were measured and collected, that model with winged columns behave well was testified. And the reinforcement method of balancing stiffness and increasing ductility is put forward. The results provide a foundation for the retrofitting design of the existing houses.

In linear system, in-plane motions are decoupled from out-of-plane motions for planar frame structures. A theoretical method is proposed that permits the efficient calculations of modal characteristics of planar multi-story frame structures. There are 3 × m beam components for a planar m-story frame structure. By analyzing the transverse and longitudinal motions of each component simultaneously and considering the compatibility requirements across each frame joint, the undetermined variables of the entire m-story frame structure system can be reduced to six, regardless of the number of stories, and that can be determined by the application of the boundary conditions. The main feature of this method is to decrease the dimensions of the matrix involved in the finite element methods and certain other analytical methods.

The paper reports the analytical investigation in Multi-storey building located in seismic zone III. This zone is considered as moderate-damage risk zone as per Indian Codal provision and thirty percent of India falls in this category. To improve the seismic performance, externally bonded FRP strengthening techniques are adopted to deficient beam and columns, in this paper, the analysis of building is carried out with and without lateral resisting system (Shear wall) and retrofitting is done by wrapping the deficient beams and column using Carbon Fiber Reinforced Polymer (CFRP sheet) to evaluate the performance of upgraded structural element.