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Abstract. This paper is concerned with an accurate prediction of the effects of adjacent structures on the blast loads on a building in urban terrain. Blast loadings on structures have typically been evaluated using empirical relationships. These relationships assume that there are no obstacles between the charge and the target. In real situations, the actual blast loads can either be reduced due to shadowing by other buildings or can be enhanced due to the presence of other buildings in the vicinity. Results of the numerical simulations presented in this study for multiple buildings in an urban environment have demonstrated the importance of accounting for adjacent structures when determining the blast loads on buildings. An approach to determining the enhancement factors is described.

Ballasted railway track is very suitable for heavy-rail networks because of its many superior advantages in design, construction, short- and long-term maintenance, sustainability, and life cycle cost. An important part of the railway track system, which distributes the wheel load to the formation, is the railway sleeper. Improved knowledge has raised concerns about design techniques for prestressed concrete (PC) sleepers. Most current design codes for these rely on allowable stresses and material strength reductions. However, premature cracking of PC sleepers has been found in railway tracks. The major cause of cracking is the infrequent but high-magnitude wheel loads produced by the small percentage of irregular wheels or rail-head surface defects; both these are crudely accounted for in the allowable stress design method by a single load factor. The current design philosophy, outlined in Australian Standard AS1085.14, is based on the assessment of permissible stresses resulting from quasi-static wheel loads and essentially the static response of PC sleepers. To shift the conventional methodology to a more rational design method that involves a more realistic dynamic response of PC sleepers and performance-based design methodology, comprehensive studies of the loading conditions, the dynamic response, and the dynamic resistance of PC sleepers have been conducted. This collaborative research between several Australian universities has addressed such important issues as the spectrum and the amplitudes of dynamic forces applied to the railway track, evaluation of the reserve capacity of typical PC sleepers designed to AS 1085.14, and the development of a new limit states design concept. This article presents the results of the extensive analytical and experimental investigations aimed at predicting wheel impact loads at different return periods (based on field data from impact detectors), together with an experimental investigation of the ultimate impact resistance of PC sleepers required by the limit states design approach. It highlights the reliability approach and rationales associated with the development of limit states and presents guidelines pertaining to conversion of AS 1085.14 to a limit states design format. The reliability concept provides design flexibility and broadens the design principle, so that any operational condition could be catered for optimally in the design.

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Composite materials, including Fibre Reinforced Polymer (FRP) bars, have been gaining momentum as alternatives to traditional steel reinforcements in civil and structural engineering sectors. FRP materials are non-corrosive, non-conductive, and lightweight and possess high longitudinal tensile strength, which are advantageous for their use in civil infrastructure. This paper presents the results of an experimental investigation into the effects of the use of glass FRP (GFRP) bars as internal reinforcement on the behaviour of concrete beams. Both static and dynamic (impact) behaviours of the beam have been investigated. Twelve GFRP reinforced concrete (RC) beams were designed, cast and tested. Six GFRP RC beams were tested under static loading to examine the failure modes and associated energy absorption capacities. The remaining six GFRP RC beams were tested under impact loading using a drop hammer machine at the University of Wollongong. GFRP RC beams with higher reinforcement ratio showed higher post cracking bending stiffness and experienced flexural-critical failure under static loading. However, GFRP RC beams under impact loading, regardless of their shear capacity, experienced a "shear plug" type of failure around the impact zone. Energy absorption capacities of beams were determined. The average dynamic amplification factor was calculated as 1.15, indicating higher dynamic moment capacities compared to static moment capacities (15-20% increase). Reinforcement ratio and the strength of concrete influenced the behaviour of GFRP RC beams. -------------------------------------------------------- * Corresponding authors Research Highlights Flexural behaviour of GFRP RC beams has been investigated. Twelve GFRP reinforced concrete (RC) beams were designed, cast and tested. Six GFRP RC beams were tested under static loading to examine the failure modes and associated energy absorption capacities. The remaining six GFRP RC beams were tested under impact loading using a drop hammer machine at the University of Wollongong. GFRP RC beams with higher reinforcement ratio showed higher post cracking bending stiffness and experienced flexuralcritical failure under static loading. However, GFRP RC beams under impact loading, regardless of their shear capacity, experienced a "shear plug" type of failure around the impact zone. Energy absorption capacities of beams were determined. The average dynamic amplification factor was calculated as 1.15, indicating higher dynamic moment capacities compared to static moment capacities (15-20% increase). Reinforcement ratio and the strength of concrete influenced the behaviour of GFRP RC beams.