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This study presents a numerical analysis to reduce the overpressure inside protective tunnels for external detonations. A three-dimensional computational fluid dynamics model of a tunnel subjected to detonation for a hemispherical charge with a charge weight of 555 kg and a standoff distance of 7.6 m was established, based on a mesh sensitivity study to obtain an optimal element size, stability analysis of overpressure, and validation study to evaluate the accuracy of the numerical results based on Unified Facilities Criteria (UFC) 3-340-02. A parametric analysis was performed using the validated numerical model to investigate the effects of the entrance shape and blast pockets on the reduction in the maximum overpressure. The maximum overpressures were effectively reduced as the slope angle of the tunnel entrance decreased and the length of the blast pocket divided by the tunnel width decreased. An optimized shape of the tunnel was proposed based on the numerical results, where the peak overpressures were reduced by a maximum of 64.5%. This study aims to protect facilities, personnel, and equipment and further reduce construction costs by lowering the overpressure rating of blast valves in protective tunnels.

The early discovery of factors that compromise a civil infrastructure’s structural integrity allows for safety monitoring, timely prevention, and a prompt remedy to the discovered problem. As a result, researchers have been researching various methodologies and types of structural health monitoring (SHM). A systematic search was performed following the updated Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA 2020) in Scopus and ScienceDirect from Elsevier, Google Scholar, MDPI, Springer, Wiley Online and ASCE Library, EOP and IOP Science, IEEE, and other databases with the reliable peer review process. From 1480 identified pieces of literature, one hundred and nine (109) sources met the criteria for inclusion and exclusion and were used to produce our findings. This study presents the identified purpose and application of image-based SHM, which includes: (1) identifying and discovering; (2) measuring and monitoring; (3) automating and increasing efficiency; and (4) promoting development and creating 3D models. Furthermore, the responsibilities and relevance of components and parameters for implementing image-based SHM devices and systems, and their issues, are covered in this paper. Future research can benefit from the stated applications for innovation and the requirements of image-based SHM.

A series of earthquake events give impetus to research on the ductile fracture behavior of steel materials. In the last decades, many fracture models have been developed and utilized in the mechanical or aerospace engineering. Nevertheless, very little application to structural members used in the construction industry has been made due to the lack of a suitable model for the fracture behavior of constructional steel. This paper presents the experimental and finite element (FE) technique to predict ductile fracture in mild carbon structural steel (SS275) sheets, which has been widely used in building structures. The post-necking true stress–strain responses were successfully estimated using the weighted-average method. The Bao and Wierzbicki (BW) model, which requires only two model parameters, was selected for the identification of fracture locus. Each model parameter was calibrated from uniaxial tension and in-plane shear specimens with the aid of digital image correlation (DIC) and finite element analysis. Fracture simulation was then performed and validated based on the experimental results of the specimens under combined tension and shear stress state.

The block shear equations specified in the current AISC specification for structural steel buildings and North American cold-formed steel design specifications are based on research results of carbon steel bolted connections. These equations were found to be inapplicable for the welded connections in the literature. This issue is primarily associated with the use of the incorrect assumption on block shear failure mechanism. The present paper examines the accuracy of various block shear equations available in the design specifications and in the literature. The paper also examines the shear hardening capacity and the level of tensile stress over the critical net area with the results of finite element analysis, in which the fracture simulation is considered. It shows that the block shear capacities of lean duplex stainless steel welded connections can be predicted accurately using tensile stress equal to 1.25Fu, as proposed in the literature.

Explosions and fire have very critical safety hazard impacts on offshore oil and gas facilities since they are mostly located in remote areas and could induce serious environmental issues. Explosion risk assessment and structure blast analysis are essential for these production facilities, and research studies have been carried out. Explosion due to blowout during drilling operation is also a critical risk for drilling units, and this has not been researched much until the accident of the drilling unit in the Gulf of Mexico in 2010. This paper provides the risk and evaluation of explosion and structure under blast pressure during the drilling operation, whereas previous research studies have mainly been interested in process plants. This study suggests weight saving in drilling units through the consideration of the actual behavior of gas explosion. Weight saving is the priority of offshore unit design due to payload. This research also gives guidelines to select the material-grade-appropriate anti-explosion system through the comparison of several materials by design and result.