Journal of Performance of Constructed Facilities

The built environment is the product of complex interactions between the external environment, the building materials, the design, the contents, the activities in the building, and the occupants, both human and commensal. To try to manipulate any one of these factors without consideration for the effects on the others can be at worst ineffective, and at best, inefficient and costly. Timber decay organisms cannot be eradicated even by the most Draconian pesticide treatments. However, they can flourish in buildings only if the environmental conditions are suitable. Even with the loss of traditional skills and the complexities introduced into building by new materials and uses, these conditions can easily be avoided with a little thought and scientific understanding. Indeed, new materials and techniques can often be used to advantage if their properties are analyzed as potential environmental controls. This more rational approach to the treatment of timber decay is really good building practice, which independent surveyors and their scientific consultants should promote in the interest of sound building and public health.

The purpose of this paper is to describe the cause of distress to the foundation and slab of an old post office building, and to discuss several remedial options. The subsurface investigation program revealed a relatively unique soil condition. The subsurface conditions generally indicated an in-place uncontrolled fill layer consisting of highly plastic soils with variable amounts of gravel, debris, brick, glass fragments, clam shell pieces, scrap metal, and coal ashes. The fill layer was followed by clayey sandy gravel, sandy silt, and sandy clay overlying limestone conglomerate bedrock. Layers of very loose sand-silt-rock mixture were noted below the soil/rock interface. The highly fractured rock appeared to have voids (cavities) filled with silt-sand mixtures. These voids may have been formed as a result of solution activities (sinkholes) in limestone conglomerate formation. Two categories of remedial approaches, namely deep and shallow remediation, are discussed with regard to their economical and potential risk implications.

Loads during construction are highly variable and are often far in excess of what might be considered reasonable for purposes of design. While formwork design is still generally the responsibility of the contractor, increased attention is being paid to the engineered design of these and other temporary support systems. The relative frequency of failures of structures during construction versus those during service suggest that an engineered approach to formwork design in certain construction situations may be warranted. In this paper, initial observations from actual shore load measurements are made and the implications for design and construction are discussed. Specific attention is paid to the shore load effect (i.e., that value of load to which the shoring element is actually subjected). The work reported in this paper is part of an ongoing project to develop recommendations for design during construction. The qualitative analysis described herein provides much needed information on the magnitude and variations in load effect. In addition, this information can be used to relate the applied loading (i.e., actual loads on the slab) to the shore load effect, thereby providing information on load-structure interaction that may be important for safe design and construction of formwork systems.

Concern about whether the tiling materials primarily developed in temperate countries would be durable enough under Singapore's tropical climate was raised after a series of falling-tile incidences. The Singapore building authority responded by launching a research project to review and investigate the entire process of external wall tiling. As part of this effort, a series of layered composite specimens were designed and fabricated by fixing different tiles on concrete slabs with various fixatives. These specimens were subjected to accelerated weathering tests after curing, then tested destructively with chosen yardsticks of pull-off and shear-off strengths, together with the critical displacement corresponding to the commencement of the tile's break off. The findings of these tests confirm that the materials and application methods, when followed according to specification, do not intrinsically cause the falling-tile problem, and the tropical climate of Singapore is also not particularly destructive to them.

Types of failure such as bowing, increased surface absorption, and loss of strength can frequently be observed on facades even a few years after installation if crystalline calcite marble is used. The investigation discussed evaluated the processes taking place in the structure of marble that lead to such damage. By means of a dilatometer the anisotropic thermal expansion of a coarse-grained marble type was measured systematically under temperatures between 20 and 200°C. The thermal expansion coefficient α amounted to between 15 ± 2$\dot{s}$10⁻⁶ K⁻¹ and 0 ± 2$\dot{s}$10⁻⁶ K⁻¹, depending on the orientation of the specimens, thus showing an extremely pronounced anisotropy. Special attention was paid to residual dilatation in the marble specimens that remained after the first heating-cooling cycle of the individual specimen (hysteresis). The dilatometric measurements were compared with investigations of acoustic emission (AE), which were carried out during the dilatometric measurements. These AE measurements provided information about the phase in the heating-cooling cycle during which the marble structure was damaged most by microcracks at the grain boundaries. The results proved that measuring AE signals is a suitable method of determining and analyzing thermal microfracturing of marble.

Subgrade soils supporting a 0.3 m diameter sewer pipe settled approximately 50 mm, and caused approximately 21% of the 730-m-long pipeline to be removed and replaced. The paper analyzes several reasons for the failure, and presents several lessons learned from the failure. Characterization of the subsurface conditions and incorporation of these results during design and construction could have prevented the failure. In addition, inspection and testing of the subgrade soils followed procedures developed based on the assumption that the subsurface conditions had been adequately characterized. The paper points out several problems relating to the roles during design and construction of the municipal agency, the water district, the geotechnical engineer, and the contractor on the project. The division of construction inspection responsibilities on the project led to a crucial part of the project (the trench bottom) not subject to any inspection. The cost of the pipe replacement was more than 30 times the cost of a detailed subsurface investigation that should have been performed for the project.