Effects of connection types and elevated temperature on the impact behaviour of restrained beam in portal steel frame

Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experimental measurement and numerical simulation techniques. Comprehensive parametric studies are carried out to discuss the influence of end connection types, temperature, impact velocity,impact mass and span-to-depth ratio(SDR) on the dynamic response of the beams. The characteristics of deformation, internal force and energy distribution about the restrained beams and its joints are investigated. A temperature dependent criterion for evaluating the frame joint performance is proposed to measure the degree of performance degradation and impact resistance of the joint. The dynamic displacement amplification factor in different temperature environments are proposed for the different beam end constraint types and SDRs. Results of the experimental and numerical analysis show that the welded connection(WC) of three typical joint types is the strongest, and the extended endplate connection(EEC) is the weakest in terms of the impact resistance performance. With regard to the failure mode of the joint, the failure positions of the WC and the welded-bolted connection are located in the inner web of the column. Meanwhile, the EEC is located in the connection position between the beam and the endplate. Three different internal force stages and two obvious critical temperature boundaries of the restrained beams emerge with the increase in temperature, and they have significant characteristics in terms of deformation trend, internal force transfer and energy distribution. During the impact, a phenomenon known as “compression arch action” develops into “catenary action” with the increase in deflection in the frame beam mechanism.

Auditory abnormalities in children with autism

The present study aimed to describe the characteristics of auditory abnormalities present in cases of autism. One hundred and fifty six children with autism and 141matched controls with language delay were investigated via direct observations combined with parent/caregiver reports. All of the autistic individuals demonstrated auditory abnormalities especially in the domain of hyposensitivity, compared with 33.3% of children with language delay. The auditory abnormalities in autism primarily comprised of auditory hyposensitivity, auditory hypersensitivity, phonophobia, and peculiar interests in certain sounds. Participants with autism were rated as having more problems than the language-delayed children in all the items of each domain. No significant difference in the range of auditory abnormalities were observed between mild and severe autistic children except for the presence of phonophobia. Children with autism presented with diverse auditory abnormalities which may be specific features in autism and may play an important role in the early identification of autism.