STRUT-FRAMED BEAM STRUCTURE FOR RECONSTRUCTION OF PEDESTRIAN BRIDGES

A new strut‐framed beam steel structure is considered. This type structure is employed in reconstruction of pedestrian bridges. The proposed constructional design model allows replacing the two‐span beam bridge by one span strut‐framed beam. In this case the members of already existing carrying structure are employed and the service of the actual structure is not interrupted. A response of new structure to symmetric and asymmetric loadings is analysed. The analytical relations for distribution of internal forces are presented. The choice of parameters of strut‐framed beam is investigated. An efficiency of suggested structural design model is illustrated via the performed numerical simulation of strut‐framed beam.

The Effects of Seam Height, Scaling Method, and Bar Weight Distribution on Scaling Effectiveness and Electromyographic Activity

Scaling bars are frequently used in underground mining for removing loose material from the roof and the walls. Previous research has demonstrated the scaling bar to be one of the hand tools more frequently involved in underground mining muscular-skeletal injuries. The present experiment investigated the role of seam height, scaling method and selected parameters of scaling bar design. Fourteen subjects worked in simulated mine environment and participated in all conditions of the experiment. Electromyographic (EMG) data was collected to study the relative involvement of six trunk muscles, and dynamometer output measured subjects' ability to use each bar and method effectively. Results suggest the parameters of weight and weight distribution to be important in scaling bar design. Also EMG data showed differences with tool parameters and the method used. Asymmetric loadings to the spine were found to be more extreme in the low roof conditions. These results suggest recommendations concerning tool design and proper training.