MEASUREMENT OF DYNAMIC CHARACTERISTICS IN COMPOSITE BOX GIRDER BRIDGES

A dynamic measurement programme was carried out on a number of steel-concrete composite box-girder bridges with different span lengths and number of spans. The programme involved the multi-point measurement of strain and acceleration at selected locations in the bridges due to normal traffic and special test vehicles. The data acquired are used to determine bridge dynamic characteristics such as natural frequencies, modal shapes, impact factors which are about 9 to 10 percent. This value is lower than that given by the current CSA and AASHTO formula. (Author/TRRL)