Burst Strength of NPS30 Steel Pipes with Dent-Crack Defect

Pipeline is the common mode for transporting oil, gas, and various petroleum products. Structural integrity of oil and gas transmission pipelines is often threatened by damages such as dent, corrosion, crack, gouge, or any combination of these damages. Such a damage may lead to structural failure in a field pipeline. One of combined defects is dent-crack defect which is a dent defect that contains a crack defect within the dent. Hence, the pipeline operator becomes concerned about the performance and safety of the linepipe if a pipe wall is subject to a dent-crack defect. Research work using full-scale tests and finite element method was undertaken at the Centre for Engineering Research in Pipelines, University of Windsor to study the influence of various internal pressures, diameter-to-thickness ratios, dent depths, crack lengths, crack depths, crack locations, and pipe steel grade on the structural behaviour and the burst strength of NPS30 (30 in diameter) and X70 and X55 grade pipes when a dent-crack defect is developed. This dissertation discusses the experimental and numerical results obtained from this study with the conclusions drawn

Experimental and field performance of PP band retrofitted masonry: evaluation of seismic behavior.

Unreinforced masonry (URM) buildings exhibited extreme vulnerability during past earthquakes though these are shelters of majority population in many earthquake prone developing countries. Most of the current retrofitting techniques used for such structures are either expensive or requires highly skilled labor or sophisticated equipment for implementation. On the other hand, the retrofitting technique proposed in this paper is economical and easy-to-apply. This paper aims at examining the performance of the retrofitting technique using polypropylene (PP) band. The displacement controlled lateral deformation has been investigated experimentally. The monotonic load-displacement behaviors of URM wall and the wall retrofitted with PP band are compared. It was found that URM wall retrofitted by PP band improves the ductility and energy absorption capacity by three times, and two times, respectively. Performance of a full-scale masonry building retrofitted with PP band in Nepal during last Gorkha earthquake of April 25, 2015, has also been presented in this paper. It was observed that the PP band retrofitted masonry building survived while the nearby many buildings experienced severe damage and some of them collapsed. This study demonstrates the efficacy and practicability of use of PP band for improving seismic resistance of URM structure