No abstract

An active tendon control system for civil engineering cable‐supported structures is proposed. The technique is based on a tendon actuator collocated with a force sensor. A large‐scale mock‐up using industrial components has been built and widely tested. The test‐bed is a model of cable‐stayed bridge during its construction phase, equipped with hydraulic actuators on the two longest stay‐cables. The results of several damping experiences are presented; they clearly demonstrate the efficiency of the active damping system. The proposed technology is directly applicable to real structures by scaling up the devices.

The present recommendation defines a method for measuring the time-dependent strain in hardened concrete specimens that are either load-free or are subjected to a uniform compressive force kept constant over a long period. It states the definitions of autogenous shrinkage and drying shrinkage, basic creep and drying creep, instantaneous strain at a given age, and recovery. It gives the specifications for testing and measuring devices and describes, in an appendix, three types of apparatus for creep tests. The present recommendation applies to the case of concretes containing light, normal, and heavy aggregates, when the maximum size of these aggregates does not exceed 50 ram.