Seismic response trends evaluation and finite element model calibration of an instrumented RC building considering soil-structure interaction and non-structural components

Peer reviewedPostprin

Enhanced Concrete Bridge Assessment Using Artificial Intelligence and Mixed Reality

Conventional methods for visual assessment of civil infrastructures have certain limitations, such as subjectivity of the collected data, long inspection time, and high cost of labor. Although some new technologies (i.e. robotic techniques) that are currently in practice can collect objective, quantified data, the inspector\u27s own expertise is still critical in many instances since these technologies are not designed to work interactively with human inspector. This study aims to create a smart, human-centered method that offers significant contributions to infrastructure inspection, maintenance, management practice, and safety for the bridge owners. By developing a smart Mixed Reality (MR) framework, which can be integrated into a wearable holographic headset device, a bridge inspector, for example, can automatically analyze a certain defect such as a crack that he or she sees on an element, display its dimension information in real-time along with the condition state. Such systems can potentially decrease the time and cost of infrastructure inspections by accelerating essential tasks of the inspector such as defect measurement, condition assessment and data processing to management systems. The human centered artificial intelligence (AI) will help the inspector collect more quantified and objective data while incorporating inspector\u27s professional judgment. This study explains in detail the described system and related methodologies of implementing attention guided semi-supervised deep learning into mixed reality technology, which interacts with the human inspector during assessment. Thereby, the inspector and the AI will collaborate/communicate for improved visual inspection

Vibration serviceability of floors subjected to footfall loading of single and multiple occupants

There is an increasing number of modern floors designed according to current vibration serviceability design guidelines failing to provide satisfactory vibration serviceability performance. This is because the design guidelines are based on assumptions and knowledge that were available in the late 1990s and at the beginning of the 21st century. Since then, there has been developments in the construction trends towards lightweight and modular structures. Numerous number of studies were conducted in the last few years to improve design tools related to vibration serviceability of floors. However, there are still gaps where the realism of these models and design tools can be improved. This thesis aims to improve the realism of design tools related to footfall-induced vibration of floors based on the usage of floors. An improved method to take into account the influence of dynamic interaction between walking individuals and lightweight floors on the vibration response calculations is proposed. For floors in sensitive facilities, an improved model to predict vibration levels for any probability of exceedance is derived. This model is suitable for single person walking scenario which is relevant for such floors. A model for multiple pedestrian walking scenario is also developed to be utilised for other types of floors where this walking scenario is more likely to occur. To derive such a model, an advanced Ultra-WideBand location tracking system was utilised to collect data regarding people’s occupancy and movements on floors. This model was utilised to develop two approaches to predict vibration levels using a simplified method and a more comprehensive framework which includes full simulation of people’s movements and their corresponding vibration responses

Resilience Assessment of the Built Environment of a Virtual City

L'abstract è presente nell'allegato / the abstract is in the attachmen

Variable friction cladding connection for multi-hazard mitigation

Safety and serviceability design of civil infrastructure, including buildings and energy, lifeline, communication, and transportation systems, is critical in providing and maintaining services and benefits to our communities. In modern society, new constructions tend to be more flexible due to advances in material science and construction technologies. A key challenge in the design of these structures is to meet the motion requirements under operational and extreme loadings. The purpose of a motion-based design (MBD) approach is to ensure that motion requirements are met under the design loads, after which strength requirements are verified and met. A popular method under MBD is the inclusion of supplemental damping systems. For instance, several passive damping systems were introduced over the last decades, demonstrating high effectiveness at reducing seismic vibrations for buildings. These traditional passive control systems, although capable of mitigating targeted loads, are restricted to single hazard one-at-a-time due to their limited performance bandwidth. It follows that they become difficult to implement when multiple excitation inputs are considered either combined or individually, termed multi-hazards. Alternatively, one can use high-performance control systems that include active, semi-active and hybrid control systems, to adapt structural responses under different types of hazards. This work proposes and characterizes a novel high-performance control system termed variable friction cladding connection (VFCC). The VFCC leverages the motion of cladding elements to dissipate energy. It consists of friction plates upon which variable normal force is applied through an adjustable toggle system controlled by a linear actuator. When locked, the device acts as a traditional rigid cladding connection with high stiffness for daily operation and also provides maximum friction force to passively dissipate blast energy transferred to the structure. A rubber bumper is integrated to avoid collision between the structure and cladding elements under high impact loads. The VFCC, once activated under wind and seismic hazards, performs as a semi-active damping device that leverages cladding mass to reduce structural vibrations via a feedback control system. Here, a device prototype is fabricated and tested in laboratory to identify and validate its dynamic behavior. Experimental results show that the device prototype functions as designed and demonstrates its high promise for multi-hazard mitigation. In order to effectively implement the VFCC, an MBD procedure is developed and demonstrated on building examples subjected to multi-hazards. The MBD procedure includes the analytical quantification of hazards, identification of structural motion objectives, and iterative design of cladding connection parameters. The MBD approach is first developed for each hazard individually and then extended to multi-hazard design for blast, wind, and seismic loads. Numerical simulations are conducted on several building examples where the VFCC is simulated under a linear quadratic regulator controller (semi-active case) for wind and seismic loadings, and under a locked position (passive-on case) under blast load. An uncontrolled case with a traditional rigid cladding connection is used to benchmark results, and a passive-on case is simulated under wind and seismic loads also for benchmark purposes. Simulation results show that the designed VFCC is capable of reducing the response of the uncontrolled structures under the prescribed performance objectives under multi-hazard loadings. Overall, this work demonstrates the VFCC\u27s high capability of mitigating multi-hazards by leveraging motion of the cladding system, and the promise of the developed MBD approach enabling its holistic integration at the design phase