During testing of the structural reliability of a prestressed reinforced concrete bridge built in the late 1960s, the author compared the structural responses, performances and costs of jointly conducted static and dynamic load tests. In the static load test, the precision spirit leveling technique was used to measure the deflections of the deck induced by four trucks weighing about 36 tonnes each. In the dynamic load test, accelerometers placed on the main beam were used to measure the vibration frequencies following an impulse produced by a 2-tonne truck. The dynamic load test resulted in a refined finite element model of the bridge. The comparison showed that the dynamic load test can supplement the static load test for the structural testing of new bridges or be an alternative to it for the monitoring of operational bridges.

Introduction

Various structural health monitoring (SHM) codes, guidelines and recommendations have been developed abroad in recent decades to monitor the structural health of bridges. One of the first was published by the Intelligent Sensing for Innovative Structures (ISIS) research network of Canada in 2001 [50]: it presents a summary of the SHM techniques known at that time, including static and dynamic load tests and periodic and continuous monitoring. Shortly thereafter, in the United States the Federal Highway Administration (FHWA) and the International Federation for Structural Concrete (FIB) published guidelines for the development of a SHM model for monitoring strategic bridges [2] as well as for monitoring and evaluating the safety of concrete bridges [4]. These guidelines include aspects of SHM engineering applications for bridges, including the concepts of monitoring, structures and materials, inspection technology, measurement methods, implementation and data acquisition problems, systems analysis, assessment of conditions, analysis of structural reliability and LRFR (load and resistance factor rating) methodology (TRB 2001). A few years later, the International Organization for Standardization [20,21,22] presented new international standards for measuring and processing the responses to vibrations of bridges. In 2006 the European Union issued guidelines [58] with the aim of introducing, for both managers and civil engineering technicians, the SHM procedures and technologies for structural assessment, monitoring and control (SAMCO) of infrastructure systems.