Current Issue : January-March Volume : 2024 Issue Number : 1 Articles : 5 Articles
Structural health monitoring (SHM) has gained importance because many structures are approaching the end of their design life and demanding maintenance and monitoring. Low-cost solutions may push forward a widespread implementation of SHM on infrastructures but further investigation is still required to assess the performance of technically accessible, simple, and scalable low-cost systems. This work presents the development and validation of a low-cost vibration-based SHM multinode wireless system, based on the Arduino platform, for identification of modal parameters in civil infrastructures. Full details about the hardware and source code of the system are disclosed in an open repository, allowing its reproduction even by non-specialists in electronics. The sampling frequency stability of the system is experimentally characterized, and interpolation postprocessing algorithms are proposed to solve inherent limitations. The system is validated, and its performance is investigated in impulse and ambient vibration tests performed in a real-scale slab and a high-grade system. The data obtained from the proposed system in impulse tests allowed estimation of natural frequencies within 2%, and MAC values around 0.3 to 0.9, in relation to those estimated with the high-grade system. However, the low-cost system was unable to produce usable data in ambient vibration tests....
Modern bridges are monitored by an increasing network of sensors that produce massive data for bridge performance prediction. Reasonably and dynamically predicting with monitored data for the time-variant reliability of the existing bridges has become one of the urgent problems in structural health monitoring (SHM). This study, taking the dynamic measure of structural stress over time as a time series, proposes a data assimilation approach to predicting reliability based on extreme stress data with cyclicity. To this aim, the objectives of this article are to present the following: (a) a Gaussian mixture model-based Bayesian cyclical dynamic linear model (GMMBCDLM) based on extreme stress data with cyclicity and (b) a dynamic reliability prediction method in the combination of GMMBCDLM and SHM data via first-order second-moment (FOSM) method. An in-service bridge for providing real-time monitored stress data is applied to illustrate the application and feasibility of the proposed method. Then, the effectiveness and prediction precision of the proposed models are proved to be superior compared to other prediction approaches to extreme stress data with cyclicity....
Reinforced concrete shear walls connected by coupling beams are considered an efficient structural system for tall buildings subjected to lateral loads. For seismic design of such buildings, performance-based design has been commonly used in regions with strong earthquakes for its ability to achieve economical and safe design, however the use of performance-based wind design (PBWD), which permits nonlinear response of ductile elements at specific locations under wind loads is still hindered due to the lack of information regarding the performance of these elements. In addition to that, there is still a need for developing an analytical model that can represent nonlinear behavior of these elements when subjected to wind loads. Therefore, in this study two analytical models using two different methods to consider bond slip effect (Bond SP01 (BS) model and steel modification factor (SMF) model) were developed and implemented in OpenSees software and validated with a tested specimen of reinforced concrete coupling beam subjected to a simulated windstorm loading protocol. Then, a parametric study was conducted using the SMF model to investigate the effect of axial restraint, and modification of the ductility demand. Results showed that both of the models showed good agreement with the experiment, however results of the SMF model were more accurate. As for the parametric study, it was concluded that with axial restraint, the beam behavior was dominated by shear, and a slight increase of strength was observed. At ductility demand of 1:8θy, the beam performed well with no significant damage and minor residual rotations....
The goal of this exploratory article is to examine the specifics and networks within and between conservative organizations at the local, regional, and national levels in Poland. By investigating these connections in 2016 using social network analysis and interviews, we contribute to a better understanding of the growth and structure of these groups, which created the base for right-wing organizations as well as led to the success of right-wing parties in Poland and vice versa. We expect to find that the majority of far-right organization networks is vertically structured, linking those organizations at the local level with national organizations; those at the top sustain them financially and offer popularity, access to politics, and other opportunities. However, although right-wing organizations care more about the linkages with their national counterparts, we expect to find that those few local organizations that form links with like-minded local organizations emphasize grassroots activities unrelated to participation in political party activities and are less radical and more civil in their behavior and attitudes....
Freezing into ice is a complex phenomenon that presents challenges and risks in both individual and construction contexts. Work provides a concise overview of the key aspects surrounding freezing in ice. It highlights the dangers. For construction, the risks lie in compromised structural integrity, limited stability, and access difficulties. Calculating freezing in ice involves considering temperature, material properties, freezing time, ice formation, and expert consultation. Different types of freezing into ice are identified, and the freezing process is shown to be influenced by the type of ice, such as freshwater ice or sea ice. Dealing with freezing in ice requires strategic approaches, including following established procedures, utilizing proper equipment, seeking professional assistance, and adapting to changing conditions. Engineering construction aspects encompass planning, design, ground preparation, foundation design, construction techniques, material selection and monitoring. Understanding and managing freezing in ice is crucial for ensuring safety and successful construction projects in icy environments....
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