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Nowadays, engineers are widely using accelerometers to record the vibration of structures for structural verification purposes. The main obstacle for using these data acquisition systems is their high cost, which limits its use to unique structures with a relatively high structural health monitoring budget. In this paper, a Cost Hyper-Efficient Arduino Product (CHEAP) has been developed to accurately measure structural accelerations. CHEAP is a system that is composed of five low-cost accelerometers that are connected to an Arduino microcontroller as their data acquisition system. Test results show that CHEAP not only has a significantly lower price (14 times cheaper in the worst-case scenario) compared with other systems used for comparison but also shows better accuracy on low frequencies for low acceleration amplitudes. Moreover, the final output results of Fast Fourier Transformation (FFT) assessments showed a better observable resolution for CHEAP than the studied control systems. This research was funded by the Spanish Ministry of Economy and Competitiveness, grant number BIA2017-86811-C2-1-R; the Spanish Ministry of Economy and Competitiveness, grant number BIA2017-86811-C2-2-R; the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya, Catalunya, Spain, grant number 2017 SGR 1482; Spanish Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant, grant number PRE2018-083238; Shanghai Qizhi Institute, grant number SYXF0120020109.

This paper presents the application of the observability technique for the structural system identification of 2D models. Unlike previous applications of this method, unknown variables appear both in the numerator and the denominator of the stiffness matrix system, making the problem non-linear and impossible to solve. To fill this gap, new changes in variables are proposed to linearize the system of equations. In addition, to illustrate the application of the proposed procedure into the observability method, a detailed mathematical analysis is presented. Finally, to validate the applicability of the method, the mechanical properties of a state-of-the-art plate are numerically determined, Este artículo presenta la aplicación de la técnica de observabilidad para la identificación de sistemas estructurales de modelos 2D. A diferencia de las aplicaciones anteriores de este método, las variables desconocidas aparecen tanto en el numerador como en el denominador del sistema de matriz de rigidez, lo que hace que el problema sea no lineal e imposible de resolver. Para llenar este vacío, se proponen nuevos cambios en las variables para linealizar el sistema de ecuaciones. Además, para ilustrar la aplicación del procedimiento propuesto en el método de observabilidad, se presenta un análisis matemático detallado. Finalmente, para validar la aplicabilidad del método, se determinan numéricamente las propiedades mecánicas de una placa de última generación

Nowadays,low-cost sensors and acquisition devices have been emerging as an obvioussolution to many innovative applications such as Structural Health Monitoring (SHM) systems. In this paper,issues regarding dynamic data acquisition,as well as their respective solutions,are presented. Moreover, a comprehensive description through-out an inexpensive sensor network system using open-source hardware for a real-time acceleration data acquisition has beenpresented. The platform consists of an accelerometer, an Arduino board,and a computeras a data recorder and presenter. Data is recorded through an efficient microcontroller code that can provide a considerable reading frequency (up to 300Hz). Using Python, instant acceleration recording for all the threeaxes has been done. It is shown how the performance of the proposed system is efficientfor the field of SHM systems. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R directed by José Turmo and BIA2017-86811-C2-2-R, directed by Jose Antonio Lozano-Galant. All these projects are funded with FEDER funds. Authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the funding provided through Agaur (2017 SGR 1481). It is also to be noted that funding for this research has been provided for MR. SEYEDMILAD KOMARIZADEHASL by Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant (PRE2018-083238).

In recent years, many scholars have dedicated their research to the development of low-cost sensors for monitoring of various parameters. Despite their high number of applications, the state of the art related to low-cost sensors in building monitoring has not been addressed. To fill this gap, this article presents a systematic review, following well-established methodology, to analyze the state of the art in two aspects of structural and indoor parameters of buildings, in the SCOPUS database. This analysis allows to illustrate the potential uses of low-cost sensors in the building sector and addresses the scholars the preferred communication protocols and the most common microcontrollers for installation of low-cost monitoring systems. In addition, special attention is paid to describe different areas of the two mentioned fields of building monitoring and the most crucial parameters to be monitored in buildings. Finally, the deficiencies in line with limited number of studies carried out in various fields of building monitoring are overviewed and a series of parameters that ought to be studied in the future are proposed.

Structural Health Monitoring (SHM) is essential to assess the accuracy of durability predictions of structures. Using low-cost sensors on structural evaluation has gained significant attention compare to high-cost sensors. Although these may not be as accurate and sensitive as the expensive electronic devices, with efficient code and right use, there is a possibility of getting useful information from them. These sensors can vary based on their functionality and the measurements they provide. For example, one is highly sensitive to the light of its environment while the other kind would give different results in different temperatures. In this paper, three different displacement measuring sensors have been studied. An ultrasonic sensor (HC-SR04) and two different types of laser sensors (VL53L0X and VL53L1X) are investigated in the paper. An Arduino Mega has captured their measured data, and a raspberry pi has made the acquisition. Not only issues regarding coding and placing of these sensors have been presented ultimately, but precise solutions for the aforementioned problems as well as an efficient way of assembling all the sensors are also presented in this paper. The data generated from these electronic devices can be used for Structural Health Monitoring applications. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R directed by José Turmo and BIA2017-86811-C2-2-R, directed by Jose Antonio Lozano-Galant. All these projects are funded with FEDER funds. Authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the funding provided through Agaur (2017 SGR 1482). It is also to be noted that funding for this research has been provided for MR. SEYEDMILAD KOMARIZADEHASL by Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant (PRE2018-083238).

Temperature and humidity measurements provide useful information on multiple areas of civil engineering application such as Structural Health Monitoring (SHM), Structural System Identification (SSI) and structures rehabilitation. Majority of the existing commercial systems are so costly and also these measurement paradigms need many reference spots for a full-scale structure. The aforesaid paradigms are based on collecting data through smart devices, transferring information to each other and in the final stage processing the obtained information collaboratively through cloud computing or the others technologies. Taking into account the above information and obstacles, utilizing the Open Source Platforms (OSP) microcontrollers like Arduino as well as low cost sensors are attracting more and more attention. This paper gives a comprehensive information about the most determinant aspects of the aforementioned kits in terms of their pros and cons, installation procedure, communication protocol, number of the required connections and specific characteristics of the data acquisition system, Las mediciones de temperatura y humedad proporcionan información útil en múltiples áreas de aplicación de la ingeniería civil, como la monitorización de la salud estructural (SHM), la identificación de sistemas estructurales (SSI) y la rehabilitación de estructuras. La mayoría de los sistemas comerciales existentes son muy costosos y además estos paradigmas de medición necesitan muchos puntos de referencia para una estructura a escala real. Dichos paradigmas se basan en la recogida de datos a través de dispositivos inteligentes, la transferencia de información entre ellos y, en la etapa final, el procesamiento de la información obtenida de forma colaborativa a través de la computación en la nube u otras tecnologías. Teniendo en cuenta la información y los obstáculos anteriores, la utilización de microcontroladores de plataformas de código abierto (OSP) como Arduino, así como de sensores de bajo coste, está atrayendo cada vez más atención. Este artículo ofrece una información exhaustiva sobre los aspectos más determinantes de los kits mencionados en términos de sus pros y sus contras, el procedimiento de instalación, el protocolo de comunicación, el número de conexiones necesarias y las características específicas del sistema de adquisición de datos.

Structural Health Monitoring (SHM) is basic to survey the exactness of strength forecasts of structures. Utilizing low-cost sensors on structural assessment have increased in contrast with using high-cost sensors. Although these may not be as exact and accurate as of the costly electronic gadgets, with an effective code and right use there is a probability of getting helpful data from them. The information produced from these low-cost sensors can provide useful insight for the SHM systems. In this paper problems regarding angular data acquisition together with their respective solutions are presented. Not only issues regarding coding and placing of these sensors have been presented completely, but precise solutions for the aforementioned problems as well as an efficient way of assembling and preparing the sensors have also been presented. The proposed circuit is composed of an accelerometer, a gyroscope, a magnetometer, an Arduino board and a Laptop, as an information recorder and moderator. The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding pro-vided through the research project BIA2017-86811-C2-1-R directed by José Turmo and BIA2017-86811-C2-2-R, directed by Jose Antonio Lozano-Galant. All these projects are funded with FEDER funds. Authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the fund-ing provided through Agaur (2017 SGR 1481). It is also to be noted that funding for this research has been provided for MR. SEYEDMILAD KOMARIZA-DEHASL by Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant (PRE2018-083238).

Due to serious damage of concrete structures caused by natural hazards and accidents, evaluating dynamic response of these structures is one of the most important objectives in the field of engineering. In this article, a case study is carried out in order to understand influences of blast load on a concrete bridge. In order to do so, 3D Finite Element Method (FEM) has been used to assess the dynamic response of the bridge and the failure zone for the detonation a of different amount of TNT, on the bridge deck. The results indicate that detonation of 1630 kg TNT causes 12 meters’ failure on the bridge deck. This amount of destruction is twofold greater than the failure occurred during the explosion of 1000 kg TNT. It can be expressed as follows: when the amount of TNT increases by 39%, the destruction of the bridge deck will increase by 100%.

In the last years, more and more studies highlight the advantages of complementing traditional master classes with additional activities that improve students´ learning experience. This combination of teaching techniques is specially advised in the field of structural engineering, where intuition of the structural response it is of vital importance to understand the studied concepts. This paper deals with the introduction of a new (and more encouraging) educational tool to introduce intuitively students in the dynamic response of structures excited with an educational shaking table. Most of the educational structural health monitoring systems use sensors to determine the dynamic response of the structure. The proposed tool is based on a radically different approach, as it is based on low-cost image-recognition techniques. In fact, it only requires the use an amateur camera, a black background and a computer. In this study, the effects of both the camera location and the image quality are also evaluated. Finally, to validate the applicability of the proposed methodology, the dynamic response of small-scale buildings with different typologies is analyzed. In addition, a series of surveys were conducted in order to evaluate the activity based on student´s satisfaction and the actual acquisition and strengthening of knowledge.

The analysis of the dynamic response of a circular tunnel in three types of soil at different depths under surface detonation of a 250-kg TNT charge reveals that the tunnel peak particle velocity and the failure zone length are sensitive to the soil type and material properties. The buried tunnel in silty clay sand has the least damage; the length of the failure zone is 5 m in the longitudinal direction and 0 to 60° at the top arch.

Recently, blasting loads have come into consideration because of the large number of intentional or unintentional events that affected important structures around the world, obviously indicating that the topic is relevant for purposes of structural design and reliability analysis. This paper has evaluated the dynamic responses of buried tunnel in depths of 3.5, 7, 10.5 and 14 m for surface detonation of 1000 kg TNT charge in a surrounding sandy soil. The Kobe box shape subway tunnel was used as an example to evaluate and compare with semi ellipse, circular and horseshoe shape tunnel. The finite element software LS-DYNA has been used to model and to analyze the outcome of this project, specifically to be modeled in the area of the second interaction due to explosion. The results indicate that the circular and horseshoe tunnels are less resistant to demolition than the box shape tunnel however the semi ellipse tunnel is more resistant than the box shape tunnel.