Rolando Chacón

Wireless Sensor Networks for Strain Monitoring during Steel Bridges Launching

In this paper, an experimental test performed on a hybrid steel plate girder was subjected to concentrated loads at the end of an unstiffened panel is presented. This load was intended to produce a typical reaction of the piers while launching steel girders in bridges. In this test, strain measurements were taken with conventional pre-wired gauges as well as with newly developed wirelessly connected strain-measuring system. Both measurements were carefully compared and the accuracy of the developed system was demonstrated. Results were also compared with numerical simulations deployed with FE models and on such a basis; the reliability of the developed wireless system was proven. Finally, suggestions of potential research trends in this area are provided.

Hybrid steel plate girders subjected to patch loading

Hybrid girders have proven to be an economical alternative to homogeneous girders since they provide a greater flexural capacity. One of the potential applications of hybrid steel plate girders is their usage in bridge construction. One of the potential constructive methods of these bridges is the push launch method, in which patch loads may condition the design. The aim of this paper is to present advanced conclusions of a research work dealing simultaneously with these two fields; the hybrid typology when subjected to the particular case of patch loading. The most remarkable results of the research work are pointed out. On the one hand, it is shown that the influence of the fyf/fyw ratio (namely, the hybrid grade) is negligible for girders with largely spaced transverse stiffeners. On the other hand, it is shown that this influence can be significant if the transverse stiffeners are closely spaced. Suggestions for considering these findings on design codes are provided at the end paper.

Global plastic design of stainless steel frames

The use of stainless steel structures has increased during the last decade due to their durability, aesthetics and mechanical properties such as ductility, considerable strain hardening and excellent fire resistance. However, the majority of conducted research works have only focused on single isolated stainless steel members and advances in the analysis of stainless steel frames are limited. EN1993-1-4 does not provide global plastic design rules for indeterminate stainless steel structures, such as frames, despite their proved high ductility. On the other hand, the lack of guidance on plastic design is an obstacle for the optimal design of stainless steel structures, leading to uneconomical design. This paper presents a preliminary study on non-sway stainless steel frames with stocky hollow cross-sections. The study of the behaviour of stainless steel frames is based on numerical parametric studies, considering the nonlinear material behaviour and different stainless steel types (austenitic and ferritic). The paper deals with the redistribution of internal forces and assesses the existing methods based on global plastic design for frames with stocky cross-sections, where alternative design approaches accounting for moment redistribution and strain hardening effects are analysed in addition to traditional plastic design method. Preliminary results demonstrate that including bending moment redistribution and strain hardening effects in capacity predictions is essential for an efficient design of stainless steel structures.

From physical to digital in structural engineering classrooms using digital fabrication

In this paper, a set of digital artifacts related to simple examples of structural engineering are presented. The artifacts are real‐time applications and visualizations of typical problems students from the architecture, engineering, and construction (AEC) schools are acquainted with. The real‐time nature of the examples allow a high level of interaction between humans and the classic visualization of results, namely, bending and shear force diagrams, internal stresses distributions, and contour plots. These artifacts may provide in AEC a twofold educational target: (i) for users, to provide visual understanding in real time of typical problems that must be understood in classic lectures of structural engineering; (ii) for developers, to provide meaningful applications of applied digital fabrication using sensors, microcontrollers, and GUIs and their potential in the development of tools related to Structural Health Monitoring (SHM) and the Internet of Things (IoT) among students of the AEC sector.

Mechanical behavior of the shear-patch loading interaction on transversally stiffened steel plate girders

In this paper, the behavior of the intertwined shear and patch loading mechanisms in transversally stiffened steel plate girders is described. The phenomenological insight depicted in this paper shows the influence of the web thickness and the flange yield strength as well as the influence of the transverse stiffeners on the stress distribution, the critical loads and on the equilibrium path of this particular type of loading. A previously validated numerical model is used systematically as a simulation tool. Stress-, strain-, force- and displacement fields are exploited for the sake of inferring and idealizing the most valuable features of the depicted mechanical model.

Development of IoT applications in civil engineering classrooms using mobile devices

This paper presents academic efforts aimed at integrating methodologies associated with the use of mobile devices, the potential of the Internet of Things (IoT), and the role of experimental education in civil engineering. This integration is developed by encompassing the use of sensors, microcontrollers, civil engineering problems, app development, and fabrication. The proposal provides an explorative way of approaching the numerous possibilities that arise in civil engineering when it comes to IoT, automation, monitoring, and control of civil engineering processes. The used tools represent accessible and affordable ways for application in classrooms and in educational laboratories for beginners. The initial explorative approach implies the fusion of three realms: (i) the phenomenology and mathematics of varied civil engineering problems; (ii) the systematic use of digital fabrication technologies and electronic prototyping platforms; and (iii) the creative and visual way of developing codes provided by block‐based development platforms. This integration of perspectives is an attempt of approaching civil engineering mathematics to technology and arts with a rigorous scientific approach. A set of different examples is presented with the corresponding findings in educational terms. These examples are developed in a constructive, scaffolding‐based way and may contribute as a potential alternative in the development of open‐source teaching labs in civil engineering schools.

12.01: Global plastic design of stainless steel frames

The use of stainless steel structures has increased during the last decade due to their durability, aesthetics and mechanical properties such as ductility, considerable strain hardening and excellent fire resistance. However, the majority of conducted research works have only focused on single isolated stainless steel members and advances in the analysis of stainless steel frames are limited. EN1993-1-4 does not provide global plastic design rules for indeterminate stainless steel structures, such as frames, despite their proved high ductility. On the other hand, the lack of guidance on plastic design is an obstacle for the optimal design of stainless steel structures, leading to uneconomical design. This paper presents a preliminary study on non-sway stainless steel frames with stocky hollow cross-sections. The study of the behaviour of stainless steel frames is based on numerical parametric studies, considering the nonlinear material behaviour and different stainless steel types (austenitic and ferritic). The paper deals with the redistribution of internal forces and assesses the existing methods based on global plastic design for frames with stocky cross-sections, where alternative design approaches accounting for moment redistribution and strain hardening effects are analysed in addition to traditional plastic design method. Preliminary results demonstrate that including bending moment redistribution and strain hardening effects in capacity predictions is essential for an efficient design of stainless steel structures.