STR-929: EXPERIMENTAL TESTING OF A NEW HYSTERETIC DAMPER FOR BASE ISOLATED BRIDGES

An experimental procedure was developed to implement a simplified design method of supplemental dampers for isolated highway bridges. For seismically base-isolated bridges subjected to an earthquake, the principal modes of the structure are in the isolation level which effectively lessens the seismic base shear conveyed from the superstructure to the substructure. However, this also has the effect of increasing superstructure displacement. To control the deformation of the isolators, supplemental energy dissipating devices can be introduced into the isolation system. This may nevertheless increase the total structure base shear and the merit of adding dampers has to be evaluated properly. In this paper a new type of steel hysteretic damper is proposed and tested in combination with an elastomeric isolator using displacement controlled cyclic tests. This very simple and economic damper was designed using a simplified method presented in earlier works. First, having characterized the response of an elastomeric isolation bearing used in a real structure, a simple and economic hysteretic damper was designed in accordance with the simplified method. In the next step, the designed damper in parallel with an elastomeric isolation bearing was tested by a unidirectional displacement-controlled quasi static method. Results show that this new type of damper could be used in combination with isolators to control superstructure displacement and substructure base shear

Détermination quantitative de l'activité deshydrogénasique des boues activées au cours de l'épuration biologique

Une méthode de mesure du taux d'activité des boues activées de stations d'épuration biologique a été mise au point. Cette méthode consiste en la réduction du chlorure de 2-3-5- triphényltétrazolium, agent indicateur des déshydrogénases bactériennes ; le dosage du triphénylformazan formé à la longueur d'onde de 480 nm, après extraction dans l'éthanol, s'effectue colorimétriquement. Cette méthode permet de suivre l'état bactérien et le travail de dégradation des matières organiques au niveau des microorganismes présents dans les bassins d'épuration biologique

Confinement reinforcement for bridges in medium to high seismicity zone based on new CSA A23.3-04 approach

Recent advances in confinement reinforcement of building columns have resulted in changes in Canadian code for Design of Concrete Structures CSA A23.3-04. Bridge columns and piers may also take advantage of these advances. The purpose of this paper is to use a comparable approach to propose new equations to be introduced in future Canadian bridge design code. The adopted approach for transverse reinforcement is based on the recently developed uniaxial confinement model for concrete column at Sherbrooke University. Parametric studies have been carried out on some typical bridge columns and piers to develop equations for confinement reinforcement. An intermediate level of ductility (moderate ductility) for bridge columns and piers has been introduced, similar to that in CSA A23.3-04 building design code. Confinement reinforcement for this level of ductility has been found to be less stringent than that for ductile level. This level of ductility is suitable for regions of low to medium seismicity. The adopted approach is supported by experimental results and will provide the designer more flexibility but economical and safer seismic design of bridge columns and piers

Definition of a VR-based protocol to treat social phobia

Social phobia is an anxiety disorder that is accessible to two forms of treatment yielding scientifically validated results: drugs and cognitive-behavioral therapies. Graded exposure to feared social situations is fundamental to obtain an improvement of the anxious symptoms. Traditionally, exposure therapies are done either in vivo or by imagining the situations. In vivo exposure is sometimes difficult to control and many patients have some difficulties in using imagination. Virtual reality (VR) seems to bring significant advantages. It allows exposures to numerous and varied situations. This paper reports the definition of a clinical protocol whose purpose is to assess the efficiency of a VR therapy compared to a CBT and to the absence of treatment for social phobic patients. It explains the illness' diagnosis and its usual treatments. It exposes all the architecture of the study, the assessment tools, the content and unfold of the therapy sessions. It finally reports first results of a clinical trial in a between-group design in 10 patients suffering from social phobia. The virtual environments used in the treatment reproduce four situations that social phobics feel the most threatening: performance, intimacy, scrutiny and assertiveness. With the help of the therapist, the patient learns adapted cognitions and behaviors with the aim of reducing her or his anxiety in the corresponding real situations. The novelty of our work is to address a group of situations that the phobic patient is most likely to experience and to treat patients according to a precise protocol

Virtual reality therapy versus cognitive behavior therapy for social phobia: A preliminary controlled study

Social phobia is one of the most frequent mental disorders and is accessible to two forms of scientifically validated treatments: anti-depressant drugs and cognitive behavior therapies (CBT). In this last case, graded exposure to feared social situations is one of the fundamental therapeutic ingredients. Virtual reality technologies are an interesting alternative to the standard exposure in social phobia, especially since studies have shown its usefulness for the fear of public speaking. This paper reports a preliminary study in which a virtual reality therapy (VRT), based on exposure to virtual environments, was used to treat social phobia. The sample consisted of 36 participants diagnosed with social phobia assigned to either VRT or a group-CBT ( control condition). The virtual environments used in the treatment recreate four situations dealing with social anxiety: performance, intimacy, scrutiny, and assertiveness. With the help of the therapist, the patient learns adapted cognitions and behaviors in order to reduce anxiety in the corresponding real situations. Both treatments lasted 12 weeks, and sessions were delivered according to a treatment manual. Results showed statistically and clinically significant improvement in both conditions. The effect-sizes comparing the efficacy of VRT to the control traditional group-CBT revealed that the differences between the two treatments are trivial

Virtual Reality in Mental Health

The possible impact of VR on mental health has the potential to be even more than what is currently offered by new communication technologies such as the Internet. In fact, VR is simultaneously a technology, a communication interface, and an experience: a communication interface based on interactive 3D visualization, able to collect and integrate different inputs and data sets in a single life-like experience. Using VRT, it is possible to offer exposure therapy, the most effective form of behavioral therapy for many conditions, and to integrate it with other traditional psychotherapy methods in order to improve their effectiveness. However, the "best" evidence in evaluating the efficacy of a therapy or treatment approach are the results of randomized, controlled clinical trials. To this end the paper discusses the results of the VEPSY UPDATED - http://www.cybertherapy.info - controlled clinical trials. In these trials involving a total of 388 patients - the largest-ever controlled study in VR therapy - different virtual environments were developed and tested to be used in the clinical assessment and treatment of social phobia, panic disorders, male sexual disorders, obesity, and eating disorders