Practice Periodical on Structural Design and Construction

The West Dam of the Eastside Reservoir Project was constructed by a joint venture of the Guy F. Atkinson Company, Washington Construction (now Morrison-Knudsen Corporation) and the H. B. Zachry Company. As the excavation of the clay borrow for this project progressed, the productivity of the haul trucks decreased because of wet underfoot conditions in the borrow area. Many estimating and construction planning lessons may be learned from this unexpected construction difficulty. A primary lesson is that in planning a construction operation it is always imperative to understand the geology of the project site.

Torsional stiffness is one of the member section properties commonly used in the 3D finite-element structural analysis. The explicit formulas for the torsional properties in both thin-walled open cross sections and single thin-walled closed sections, except for multicell closed sections, can be easily found in most textbooks and structural design handbooks. This paper presents the closed forms for the torsional stiffness in both twin-cell and three-cell closed sections.

Diagnostic load testing techniques have been used to verify in situ that existing structures have the required load-carrying capacity. This paper discusses the diagnostic load testing and finite-element modeling of a two-way posttensioned concrete slab with the purpose of illustrating the features of this full-scale testing method. The slab was modeled using a commercial finite-element package and the results were verified experimentally. The test loads were applied using hydraulic jacks. Negative internal bending moments were generated at critical locations equivalent to those produced by a 92 psf (4.40 kPa) superimposed uniformly distributed load. Positive internal bending moments were also produced equivalent to those resulting from a superimposed load of 159 psf (7.61 kPa). The full-scale diagnostic load testing proved to be a valuable tool for the assessment of the structure's capacity.

Interior walls and permanent or temporary partitions must be designed to resist loadings, such as those from earthquake, wind, and other building occupancy-related forces, applied perpendicular to the plane of the walls. The purpose of this test series was to develop experimentally based limiting heights for interior, non-load-bearing, cold-formed steel wall panels sheathed with gypsum board and subject to uniformly distributed lateral loadings. The limiting heights generated for ASTM C 754-98a allow designers to meet the 1997 Uniform Building Code requirements, as well as more restrictive loading and deflection requirements if appropriate to a particular application. Limiting heights for deflection limits of L/360, L/240, and L/120 (where L is the height of the wall) are developed over the range of typical design pressures.