Search

Pipe bends are frequently used to change the direction of a pipeline. The location of bends in a pipeline system is often the location that shows high stress levels. The increase in stress is due to the high flexibility of the bend resulting from the ability of the cross-section to ovalize when subjected to bending or internal pressure. Moreover, the surface geometric characteristics of bends may lead to a host of unbalanced thrust forces caused by the internal pressure. The internal pressure results in an outward resultant force that tends to straighten out the bend causing an increase in the deformations and stress levels. This phenomenon is known as "The Bourdon effect". If this outward force is not taken into consideration, unanticipated deformations and high stress levels could occur that may not be accounted for in traditional stress analysis. A better understanding of the influence of the Bourdon effect on the elbow design parameters is required. The increase in stress levels is considered using stress intensification factors presented in current codes. In this paper, the stress intensification factors presented in the current code were revisited for the case of different loading conditions and compared to FEA results. The study showed that the direction of applied bending moment on the bend has a significant effect on the distribution and magnitude of the stresses depending on the level of applied internal pressure.

Dents are plastic deformations on a pipeline’s cross-section caused by contact with external forces. They are known to have the potential to adversely affect the structural integrity of the pipeline as they induce localized strains and stresses on the pipeline. In this study, the finite element analysis of a dented plate and an analytical approach to the determination of strains based on a dent profile are compared in a bid to develop a procedure for evaluating the strains on a dented pipeline based solely on the dent profile.

Precast Concrete Sandwich Panels (PCSP) are proposed as an enclosure of modern net-zero energy buildings as they provide high thermal insulation and efficient protection against moisture ingress. A new PCSP system has recently been developed that consists of two layers of insulation – a 51 mm Polystyrene foam panel and a grooved 25.4 mm Polystyrene board – sandwiched between two reinforced concrete layers tied together by novel Z-Shape Steel Plate Connectors (ZSPC). Some of these panels are enclosed at the top and bottom with concrete beams, commonly known as end-beams. The out-of-plane behaviour of PCSP is typically described as: fully composite, partially-composite, or non-composite; depending on the shear strength and stiffness of the interlayer connectors. To investigate the effect of ZSPC and end-beams on the out-of-plane flexural behaviour of the PCSP, six full-size panels having length, width, and thickness of 3.65 m x 1.22 m x 0.23 m, respectively, were constructed and subjected to a four-point flexural loading. The measured moment-curvature responses for all six panels were compared to theoretical non-composite and fully-composite moment-curvature relationships. Test results revealed that PCSP with ZSPC can achieve 60% to 100% of the theoretical out-of-plane flexural stiffness of a fully-composite panel. Increasing the shear strength of ZSPC improved the out-of-plane bending moment of PCSP corresponding to the design maximum deflection limit. Adding end-beams to PCSP with even small-size ZSPC improved the out-of-plane bending moment of the panel corresponding to the design deflection limit compared to that of the theoretical fully-composite panel.