This case study aimed to compare the differences in durability and prestress loss between normal-weight-concrete (NC) lightweight-aggregate-concrete (LWC) prestressed box girders, which were constructed at same time area, so as verify superiority of using synthetic lightweight aggregate (LWA) made from reservoir sediments bridges. For NCs LWCs used basic mechanical properties (compressive stren...

A (bar-and-joint) framework is a set of points in normed space with fixed distance constraints between them. Determining whether locally rigid – i.e. every other suitably close the same an isometric copy NP-hard when has dimension 2 or greater. We can reduce complexity by instead considering derivatives constraints, which linearises problem. By applying methods from non-smooth analysis, we shal...

The segmental prestressed concrete box girder of Koror-Babeldaob (KB) Bridge in Palau, which had a record span of 241 m (791 ft), presents a striking paradigm of serviceability loss because of excessive multidecade deflections. The data required for analysis have recently been released and are here exploited to show how the analysis and design could be improved. Erected segmentally in 1977, thi...

A design methodology for collapsible rib-tensioned surface (CRTS) reflectors is presented. Offset configurations are explicitly addressed. For a reflector with aperture of 10 m diameter and focal length of 7.8 m, a root-mean-square surface accuracy of about 2 mm is achievable; this result scales linearly with the diameter. The design of a 1.5 m diameter prototype is presented, and the accuracy ...