Scipedia: Revista Internacional de Desastres Naturales, Accidentes e Infraestructura Civil

COMPARATIVE STRESS ANALYSIS OF ELBOWS IN PIPING SYSTEMS APPLYING THE NORMATIVE SAFETY MARGIN

Benjamin Colucci — Thu, 08 Jun 2023 21:55:28 +0200

Elbows are components in piping systems whose primary function is to achieve a change in flow direction. Their study is relevant, since they present higher stress levels than those observed in straight sections. Early investigations determined that this effect is caused by the ovalization effect and the presence of external moments. The capacity of a cross section to ovalize when external loads are applied results in increased flexibility of the elbows by decreasing the moment of inertia compared to a straight pipe. In this work, stress levels in elbows caused by external moments and internal pressure are studied. As a case study, a series of elbows of various diameters and thicknesses with suitable characteristics for understanding the phenomenon of ovalization and the comparison of different calculation methodologies is proposed. The stresses obtained by applying the ASME B31.1 and ASME B31.3 codes are compared with those obtained by a numerical model of finite elements, through a novel indicator called the Normative Safety Margin. This indicator considers the admissible stresses established by the specifications for the materials of the accessories. Applying B31.1 Code, higher normative safety margins are obtained than those obtained with B31.3. For the entire series under study and all types of applied loads, lower normative safety margins were obtained when the accessories are more flexible.

SUSTAINABLE DEVELOPMENT OF SMART CITIES BASED ON INFORMATION TECHNOLOGY AND EDUCATION

Benjamin Colucci — Thu, 08 Jun 2023 22:03:49 +0200

Cities have become much more complex, and public agencies are facing increasing challenges to provide efficient and inclusive services to the community. Cities are highly dependent on civil infrastructure and the technologies adopted for the management of public services including transportation, energy, security, water resources, first aid, and supply chain systems. The Smart City concept is interdisciplinary in nature and represents a new way of managing civil infrastructure by identifying problems with the support of advanced technologies. Within this concept, it is necessary to model various scenarios and analyze potential outcomes to seek the best solution for the situations raised. However, the technological components are insufficient by themselves if they do not allow interaction among the parties involved in the management process. In this context, Building Information Modeling (BIM) is a tool that can improve collaboration and communication among the parties involved in the management of civil infrastructure in a city. This article describes a humanistic concept of a Smart City with emphasis on the quality of life and the role of education in its development and sustainability, integrating modern technology for an efficient interaction of health, transportation, public safety, energy, building management subsystems, among others. These interconnected subsystems must provide the services to sustain the quality of life of citizens. In this humanistic approach, practice of civic values has a fundamental role in the responsible use of resources and technological tools to transform a city into a smart one.

CONTRIBUTIONS AND INNOVATIONS IN THE GEOTECHNICAL ENGINEERING PRACTICE OF THE SOILS ENGINEERING OFFICE OF THE PUERTO RICO HIGHWAYS AND TRANSPORTATION AUTHORITY

Benjamin Colucci — Thu, 08 Jun 2023 22:11:58 +0200

The Puerto Rico Soil Engineering Office (OIS) was founded in 1975 and is currently under the Design Area of the Highway and Transportation Authority (ACT). In its foundation, the SEO was composed of a Soils Engineering Division and a Geology Division. Its main function was the subsoil exploration for the geotechnical structures designed and constructed by the PRHTA. Over time, the functions of the SEO evolved while soil engineering and rock engineering were evolving. Today, the SEO continues to attend to inquiries during projects’ design and construction phases. Additionally, the SEO attends several geotechnical initiatives like Geotechnical Asset Management and Unstable Slope Management. This article presents the contributions and innovations in the practice of geotechnical engineering that the OIS has attended and has had a leading role with emphasis on new analyzes and equipment that meet state and federal requirements and current codes that have potential to be implemented in geographic areas in the Caribbean and Latin America with similar geotechnical and geological characteristics.

REFLECTIONS ON THE DESIGN OF STEEL POLES FOR TRANSMISSION LINES IN MEXICO

Benjamin Colucci — Thu, 08 Jun 2023 22:20:24 +0200

The use of steel poles as support structures for lines in Mexico has increased in the last 30 years, mainly due to the increase in urban and suburban sprawl that demand less right of way for this type of infrastructure and less space for their foundations. To fulfill these requirements, numerous studies have been carried out related to dielectric sizing, optimization of the distance between phases to reduce electrical losses, wind hazard associated with the cable-insulator-hardware-structure-foundation system, structural design criteria based on reliability, natural-scale mechanical tests, among others. This article presents some reflections related to the different stages of the design of metal poles for transmission lines, from input data to structural designs, following the criteria of the Mexican electrical industry for a 230 kV pole, 2 circuits, located in Mexicali, B.C.

SEISMIC SOIL PRESSURES ON EMBEDDED WALLS WITH VARYING STIFFNESS AND CONTACT CONDITIONS

Benjamin Colucci — Thu, 08 Jun 2023 22:31:08 +0200

This article evaluates how the seismic pressures developed in embedded walls are affected by different wall stiffness and various contact soil-wall conditions. Several two-dimensional numerical models of an embedded wall-soil system were developed in Abaqus® by varying the wall stiffness. One model considered the wall as very rigid with a large modulus of elasticity and the other one considered the wall as flexible with original modulus of elasticity. Wall heights of 10, 20 and 30 meters were considered on the models to obtain different wall stiffness. The contact between the soil and the wall is modified by changing the friction coefficient between 0 to 0.75. The response of the soil is validated using 1D nonlinear site response analyses. The analyses are performed using records that match a narrow-band modified target spectrum for a moment magnitude of 7.70. The results show that the rigid walls developed larger seismic pressures than the flexible walls when subjected to the same earthquake records. The seismic soil pressures in the rigid walls do not change considerably by varying the contact condition between the soil and wall. Changes in the friction coefficient have a major impact on the seismic pressure distributions on flexible walls.

STATE OF PRACTICE IN NATURE-BASED/INSPIRED SOLUTIONS FOR COASTAL EROSION

Benjamin Colucci — Thu, 08 Jun 2023 22:42:55 +0200

Nature-based Solutions (NbS) are imperative now, in view of the resulting effects of climate change and man-made alterations in coastal areas. The perspective to address coastal solutions may not be possible to be limited exclusively to ecological solutions. This article, based on a literature review, focuses on hybrid solutions for coastal erosion control. The review highlights examples from around the World that can be applied to islands, having Puerto Rico (PR) as a typical scenario. It presents a summary of how gray infrastructure commonly applied in the past decades can be re-designed and adapted to integrate natural solutions. This article provides significant facts about the merits of structural, ecological, and economical aspects that should be considered on NbS projects. This article helps understand the state of practice and possible solutions that can be implemented, especially, in tropical and sub-tropical regions.

PEDESTRIAN PERFORMANCE ON MID-BLOCK CROSSINGS USING A ROAD INFORMATION ASSISTANCE SYSTEM IN A VIRTUAL REALITY EXPERIMENT

Benjamin Colucci — Thu, 08 Jun 2023 22:52:53 +0200

The increase in crash-related pedestrian fatalities, primarily in urban streets, has promoted the development of technological innovations to mitigate this global problem. This article presents the results of an experiment that used virtual reality technology to study the performance of pedestrians at mid-block crossings of urban streets and the impact of a Road Information Assistance System [RIAS]. The RIAS was simulated as a handheld device that displays warning symbols or a combination of symbols and real-time information about the vehicles approaching the crosswalk to assist pedestrians in making the crossing decision. The experiment simulated a connected urban environment that can receive and transmit data from sensors in the infrastructure, vehicles, and pedestrians [via the RIAS]. The study evaluated the walking speeds, the vehicle gaps selected to cross the street, and the number of successful crossing events with no collisions. Three groups of twelve subjects [no RIAS, simple RIAS, and complex RIAS] were selected. The age and gender of the subjects, as well as the RIAS type used to cross the street, had significant effects on the average walking speed. The distributions of the average gap accepted by each of the three groups, based on the RIAS type, were statistically different. The group that used the RIAS device displaying symbols only had the worst performance and the highest average gap accepted when crossing the street.

SMART CITIES

Benjamin Colucci — Mon, 30 May 2022 15:41:43 +0200

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