Estimating the tension acting on cables is essential for the maintenance of cable structures such as cable-stayed bridges and extradosed bridges. The safety of a cable can be assessed by comparing the tension acting on the cable and the allowable value. In the current Japanese practice, the tension of a cable is estimated using the vibration or higher-order vibration method, which considers the natural frequencies of the cable. However, recently, the wind-induced aerodynamic vibration of cables has become a problem. In such a case, dampers are installed onto the cables to suppress the aerodynamic vibration. Consequently, the damper changes the cable’s natural frequencies; thus, the vibration and higher-order vibration methods are inappropriate for estimating the tension of a cable with a damper. The authors previously developed a tension estimation method for a cable with a damper, where the cable is modeled using a tensioned Bernoulli-Euler beam. A theoretical equation that relates the natural frequencies of the cable with the tension and bending stiffness of the cable and damper parameters was derived. The method is used to inversely estimate the tension and bending stiffness of the cable and damper parameters simultaneously based on the cable’s natural frequencies. In this study, the tension estimation method is first introduced, then validated using numerical simulations, and subsequently verified via a laboratory experiment. Moreover, field measurements of a cable-stayed bridge in Japan were performed to verify this method. Results show that the tension estimation method can estimate the tension of a cable with a damper with high accuracy, thereby validating the method.

The conservation of Cultural Heritage (CH) requires the integration of experimental data in the computational models in order to improve the robustness of the structural analyses. In this scenario, the paper introduces recent results of experimental activities carried out on the Galleria dell’Accademia di Firenze (GDA-FI), a famous Italian museum complex. The work aims to investigate the dynamic behaviour of one of the Structural Units (SU) which compose the museum: the Tribuna, where the Michelangelo’s David is exhibited to the public. The experimental layout was composed by two triaxial stations roving in different positions carefully designed by considering both the architectonic features of the structure and the location of the masterpieces collected in the Tribuna, such as paintings and sculptures, which could not be moved during the measurements. The investigation activity was performed in the framework of a wider research project, DAVID "Defense of cultural heritage and Assessment of Vulnerability through Innovative technologies & Device", co-founded by Tuscany Region and Galleria dell’Accademia di Firenze with the aim to preserve the museum complex and the works of art inside. A computational model is herein proposed to illustrate the process of calibration, and its advantages in terms of model reliability, through the comparison between the experimental results and the model output itself. More in detail, the research deal with the issue related to the analyses of a portion of the structure, extracted from the whole complex, and the boundary conditions which need to be assigned in order to represent the actual interaction with the surrounding buildings. The workflow discussed in this paper is applied to the case study of GDA-FI and it represents a meaningful test bench in order to draw general remarks on the topic of historical museum complex conservation as well as the employment of Historical Building Information Modelling (HBIM) to link different sources of information to the computational models.

This paper presents a cloud-based sensing system which is developed to store autonomously only the peak acceleration data of several buildings on the web server. The sensor unit for the proposed sensing system is also developed. The developed sensor unit consists of Raspberry Pi 3B, digital MEMS accelerometer and Low Power Wide Area (LPWA) network device. Taking advantage of small transmitted data volume, LPWA network device advantageously make possible long-distance communication with such a low power as can be operated on the battery. The proposed algorithm associated with the developed sensor unit would be able to take out the peak absolute acceleration response of a structure to every single earthquake. As well as the peak response value, the sensor unit implemented into each building would send the basic structural information (such as structure type and fundamental frequency) to an web server utilizing LPWA network device. Those informations stored on the web server would provide the pseudo absolute acceleration response spectrum, notifying the relevant engineers that the data have been sent to the server.

The proposed cloud -based sensing system would provide the useful information for estimating the damage situation in the area in which the buildings are located. It has been tested utilizing the opportunity of E-Defense shake table experiments and has been also tested through the application to actual buildings.

The present study aims at building a numerical model of a long-distance single span aerial tramway with non-symmetric tracks and anchored cables at extremities. From a modeling point of view, aerial cable transport system is a nonlinear time variant structure as cables and vehicles are moving. Hence, a first step before dynamics study is to analyze the system changes by a quasi-static procedure neglecting inertia effects of the movement. It provides information on parametric evolution relative to the cable length controlled by the driving bull-wheel located at the bottom station. Results from static and quasi-static calculation are compared with experimental data measured on the real and unknown parameters are introduced in order to account for the lack of knowledge about cable length depending on several parameters as temperature, wear, permanent elongation, shortening operation etc. Identification of the correction parameters allows to update the model for a better fidelity. Finally, calculation results are applied to design acceleration and braking control curve of the moving cable in order to reduce the traveling time and increase system efficiency.

This work proposes a novel framework for realizing inspection automation through a human-in-the-loop machine-learning paradigm. Central to the robotic inspection system, a mixed-reality device is adopted, which interfaces human inspectors, civil structures, and robotic vehicles. We describe conceptually how to collect level-of-detail operational data to train a robotic vehicle, which shadows the inspection process in real-time and learns to realize automatic inspection. Among the different types of operational data, 3D models are essential in navigation, exploration, and damage mapping in complex structural spaces. We focus on the 3D model assessment resulting from the online visual simultaneous localization and mapping (SLAM) process. Important findings include that 3D model generation can be staged and registered. The quality of 3D models is comparable to an offline image-based generation process, namely, structure-from-Motion (SFM), when a quick-motion operation is conducted. We remark that such online 3D model generation can be comprehensively exploited in training robots for real-time structural exploration, damage detection, quantification, and ultimately integrating with building information modeling.

Excessive movements of architectural structures due to human activities have become a prevalent design issue in recent years. These vibrations can result in occupants’ discomfort/annoyance or malfunctioning of sensitive equipment. In an attempt to search for an economical method of resolving this issue, a new multiple-tuned mass damper (MTMD) has been designed and tested. The device consists of four steel plates cantilevered from a central hub. Each plate (wing) has a central slot that can be used for the movement of steel weights to adjust the natural frequencies of the MTMD during the tuning phase. In addition, air dampers connected to each wing provide the required damping for the optimal tuning of the MTMD. This paper details the design of this novel MTMD and provides the analytical equations developed for the tuning of the device. It also provides information on the field tuning of the device to a laboratory floor susceptible to large vibrations due to human movements. Several walking and bouncing tests were conducted at the Virginia Tech Vibration Testing Laboratory to evaluate the performance of the device in reducing excessive floor vibrations. In addition, the MTMD effectiveness to control low vibration levels, which may cause sensitive equipment malfunction, is discussed. It is concluded that the proposed device can provide an economical and effective method of floor vibration control.