Comparative study for designing the horizontal thrust blocks in pipelines for water and sewage networks

The thrust block is one of the most widely recognized methods of resisting thrust forces. This type of infrastructure should be installed in bends, dead ends, tees and wyes. Thrust blocks perform the function of transferring thrust force to the ground safely. Thrust block dimensions are designed based on hydrostatic pressures, bend angles, and soil properties in the surrounding area. Several codes exist for designing thrust blocks, but we focus on Egyptian code for design and implementation of pipelines for drinking water and sewage networks (ECDIPWSN) and the American Water Works Association (AWWA). In this methodology, the steps of thrust block design by the codes are demonstrated and applied individually to one of the published papers. The goal of the study is to find the optimum percentages between the dimensions of the block in the two codes and to compare the quantity of concrete after the block is designed by each code. Based on the research, it was found that the concrete amount of the block designed by (AWWA) is smaller than that designed by (ECDIPWSN). HIGHLIGHT Results of the study discovered the volume of the thrust block created by the AWWA method was smaller than the volume created by the ECDIPWSN method when excavation depth was low but was larger when excavation depth was large.

Organizational change failure: Framing the process of failing

Despite what we know about how organizations and their members respond to change, organizations continue to spend an inordinate amount of time confronting, mitigating, and dealing with failure during change. This special issue focuses on what happens when organizational change fails. Its goal is to enhance knowledge and advance theory regarding the processes and mechanisms that underlie the emergence of organizational change failure. In this editorial, we first take stock of the established perspectives on failure, and introduce an integrative approach to offer a more holistic account of the process of change failure. The framework constitutes a multilevel, interlocking strategy for future scholarship. It highlights how the evolving experience defines, creates, and enacts failure during change across three structures: the surface (i.e., context), intermediate (i.e., building block dimensions), and deep (i.e., enduring aspects) structures of failure. With this frame as its basis, the articles in the special issue prompt discussion of what exactly failure means for organizations and their members dealing with different accounts of change failure.

Pull-Out Tests on Injected Anchors in Tuff Masonry Elements

In this paper the results of pull-out tests on several types of injected anchors embedded in masonry elements made of yellow tuff are described and compared. Several bonded lengths and configuration of the masonry elements were considered in the tests. In particular, pull-out tests of anchors installed in single tuff stones were carried out in order to investigate the effect of masonry block dimensions on the activation of the splitting failure. Conversely, pull-out tests of anchors installed in masonry walls made of similar tuff stones were carried out in order to simulate real applications. Finally, the experimental results were compared with literature formulations in case of splitting failure, bond interface failure and masonry cone shaped failure.

Design Curves for Maximum Stresses in Blocks Containing Pressurized Bore Intersections

Intersecting bore geometries are used in a number of industrial applications such as in fluid ends of reciprocating pumps. Maximum tensile stresses at stress concentration points in the block can be many times the fluid pressure in the bores. Obtaining good estimates of the maximum stresses in the structure is necessary for making sound design decisions on the block dimensions. Finite element models of the bore intersection geometry were analyzed for ranges of bore sizes and block dimensions. Results of the finite element model were compared with predictions provided by a popular approximation method based on mechanics of materials principles. The approximation method was found to underpredict the maximum stresses in the block in almost every case analyzed. For some conditions, the maximum stresses computed from the finite element model were more than two times the predictions provided by the approximation method. Design curves, based on the ratio of the sizes of the intersecting bores, are presented for selecting block dimensions to meet desired maximum stress criteria.

Measurements of ridge sails in the Beaufort Sea

Ice pressure ridges in the southern Beaufort Sea near Tuktoyaktuk were surveyed in April 1986. Sail cross-section profiles and ice-block dimensions of ridges of extreme heights were measured at several locations along the outer edge of the landfast ice. Statistical distributions of sail heights as well as correlations between sail dimensions and between ice block dimensions are obtained. Geographical distribution of sail dimensions and longitudinal changes along individual ridges are examined. Key words: ridges, landfast ice, sea ice, ridge sails, ridge statistics, Beaufort Sea.