Journal of Performance of Constructed Facilities

An ultimate load test is conducted on two main beams of a 28‐year‐old building. The interaction effects of floor slabs with the adjacent structural members are investigated using the finite element method. The test arrangement results in an upward point‐load at midspan for one beam and a downward distributed load around the central one‐third span for the other. At the maximum loading, the first beam under the point‐load fails in a shear mode when the shear force reaches 120% of its ultimate capacity. The second beam under the distributed load does not fail, due to the slab‐beam interaction effect, which distributes some load to the adjacent structural members and consequently reduces the shear force carried by the beam to about 98% of its ultimate capacity. Structural capacities determined experimentally are compared with those calculated based on the in situ material strengths resulting from nondestructive tests. The comparisons show that the ultimate strength of structural members of an existing building can be accurately obtained when the in situ material properties are used.

The precollapse state of certain Howe trusses, composing the supporting structure of a timber roof construction over a harbor store building in Poland, has been investigated in the form of a case study. The usual performance and characteristic attributes of Howe trusses are described generally. The appropriate background and history of the analyzed structure is given. Potential deterioration factors are reviewed. Visible excessive deflections of the trusses suggested computer examination of the Howe truss, considering its two possible statical extremes: simply supported and three‐hinged systems. The effects of several deflection sources (i.e., dead and live load, uniform and linear changes of moisture, and slips at the lower chord splices or supports) were analyzed. While the latter showed major influence on the truss deflections, the moisture changes appeared to be of secondary importance.

The paper describes the failure and repair of a fill slope at Caminito Muirfield Street, La Jolla, California. There were several factors that contributed to the movement of the fill slope and the damage to the condominiums. One factor is that the condominiums were built very close to the top of slope, and when there was deformation due to slope creep, it damaged the rear of the condominiums. Another factor in the slope movement was the presence of topsoil, which was left in place during grading operations. Topsoil is an undesirable material because of both its low shear strength and the presence of organics, such as roots, which will decompose with time. The repair of the fill slope consisted of the complete removal of the slope failure mass and the construction of a fill buttress. A key was excavated into bedrock and the buttress was constructed using decomposed granite fill and layers of geogrid. The buttress was designed and constructed so that the final factor of safety for the rebuilt slope was at least 1.5.

The purpose of this paper is to describe the cause of distress to buildings H and J at the Calavo Woods Condominiums. The damage resulted in a lawsuit, during which the writer presented expert testimony for one of the cross‐defendants. It was observed that the greatest amount of damage occurs at the area of the maximum angular distortion of the foundation. The damage at this area, classified as severe, included interior wall‐board cracks, distortion of window and door frames, floors sloping noticeably, and walls leaning or bulging noticeably. The results of subsurface exploration revealed shallow expansive fill overlying natural red‐brown expansive clay. The soil is classified as a highly expansive clay of high plasticity. The foundation displacement and severe damage was caused by differences in moisture content of the red‐brown clay. On one side of the foundation, added moisture caused the clay to expand and the foundation to heave, while on the other side of the foundation, where the clay was drier, perhaps even shrinkage of the clay caused settlement of the foundation. The main lesson learned from this case history is the mistake in putting planter areas directly adjacent to the perimeter of the foundation.

Shortly after a taxiway and apron extension project was completed on a small airfield in Florida, depressions began to appear in some areas of the pavement surface. The extent and locations of these depressions coincided with the parking locations of various aircraft that had remained on the pavement overnight, but only on some portions of the pavement. The writer was retained by the airfield owner to determine the cause of distress and recommend a repair strategy. Nondestructive testing is conducted over the entire apron and taxiway, and test pits are excavated at selected locations. The results of laboratory and field tests, described in the paper, show that this failure is due to consolidation or densification of the low‐density recycled‐asphalt base course used in the problem areas. The low density is probably a result of inadequate compaction during construction. The paper also addresses the structural pavement design requirements and recommends a repair strategy.