This paper describes the structural aspects of the collapse of the Concorde overpass, crossing Autoroute 19, in Laval, north of Montréal. The original design and the reinforcing details for the thick cantilever slab that failed are discussed. Results from testing a simulated portion of the bridge with as-designed and as-built details are presented. The structural analysis results, by using various bridge design codes to determine the design forces, are compared. The results from nonlinear finite-element analysis, simulating the concrete deterioration, are used to explain the cause of failure of the thick cantilever slab under essentially its self-weight after 36 years in service.

For sustainable development in the construction industry, blast furnace slag has been used as a substitute for cement in concrete. In contrast, steel-making slag, the second largest by-product in the steel industry, is mostly used as a filler material in embankment construction. This is because steel-making slag has relatively low hydraulicity and a problem with volumetric expansion. However, as the quenching process of slag has improved recently and the steel making process is specifically separated, the properties of steel-making slag has also improved. In this context, there is a need to find a method for recycling steel-making slag as a more highly valued material, such as its potential use as an admixture in concrete. Therefore, in order to confirm the possibility of using electric arc furnace (EAF) oxidizing slag as a binder, a comparative assessment of the mechanical properties of concrete containing electric arc furnace oxidizing slag, steel-making slag, and granulated blast furnace (GBF) slag was performed. The initial and final setting, shrinkage, compressive and split-cylinder tensile strength of the slag concretes were measured. It was found that replacing cement with EAF oxidizing slag delayed the hydration reaction at early ages, with no significant problems in setting time, shrinkage or strength development found.

This paper provides a summary of the damage to industrial facilities in the M_w 8.8 Chile earthquake of 27 February 2010. The types of damage observed include failure of elevated tanks, collapse and cracking of concrete silos, buckling of steel silos, collapse of conveyor systems, failure of steel bins, and failure of anchor rods. Damage to industrial buildings included buckling of bracing members, failure of brace connections, shear failures of reinforced concrete columns, and shear failures of heavily loaded steel girders. Aspects of the current Chilean design code for industrial structures are reviewed and discussed. Recommendations are proposed for the development of Canadian seismic design provisions for industrial structures.

Vertical loading tests are reported for six double-sided, high-strength concrete corbel specimens. The primary variables of the investigation were the percentage of steel fibers and the anchorage method of the main tension tie. The test results indicated that performance in terms of load-carrying capacities, stiffness, ductility, and crack width was improved, as the steel fibers were added and the percentage of steel fibers was increased. The corbel specimens with headed bars used as the main tension-tie reinforcement showed superior load-carrying capacities, stiffness, and ductility compared with the corbel specimens in which the main tension ties were anchored by welding to the transverse bars. From the test results, it is expected that the load-carrying capacities, serviceability, and durability of high-strength concrete corbels would be improved by using steel fibers and headed bars. Experimental results presented were also compared with various prediction models.

Incremental Dynamic Analysis (IDA) was used to evaluate the seismic response of straight, continuous 4-span bridges with different sub-structure configurations. Three different record sets were chosen to represent three different earthquake types which can occur for a site such as Vancouver (i.e., crustal, subduction interface, and subduction inslab earthquakes). Seventy eight records were considered in each set (i.e., a total of 234 records) and the capacities of the bridges were evaluated using a fast IDA algorithm. A simplified method to account for the effects of spectral shapes was used. Different subsets of the records with specific characteristics were also used in the IDA. The bridges were designed and evaluated for two different design force modification factors and bridges with different degrees of irregularity were studied. Comparisons of the IDA results obtained indicated that in most of the cases the interface record sets resulted in lower median collapse capacities and hence were the most critical of the ground motions studied.

Inelastic dynamic analyses were carried out using 3D and 2D models to predict the mean seismic response of four-span reinforced concrete (RC) bridges considering directionality effects. Two averaging methods, including an advanced method considering displacement direction, were used for the prediction of the mean responses to account for different incident angles of ground motion records. A method was developed to predict the variability of the mean displacement predictions due to variability in the incident angles of the records for different averaging methods. When the concepts of averaging in different directions were used, significantly different predictions were obtained for the directionality effects. The accuracy of the results obtained using 2D and 3D analyses with and without the application of the combination rules for the prediction of the mean seismic demands considering the incident angle of the records was investigated. The predictions from different methods to account for the records incident angles were evaluated probabilistically. Recommendations were made for the use of the combination rules to account for the directivity effects of the records and to predict the actual maximum displacement, referred to as the maximum radial displacement.