Identification of vertical restraint stiffness of pier foundation for continuous-beam bridges

With the progress of engineering technology, the natural frequency of structures can be easily obtained by dynamic testing. If the relationship between the fundamental frequency and the constraint stiffness is analyzed, the constraint stiffness of the foundation can be identified. To this end, the vertical vibration of piers is first carried out, and a dynamic identification method for constraint stiffness is proposed. Relying on a project example of a bare pier, the vertical fundamental frequency of the test pier is measured by the pulsation method. Then the finite element software is used to establish a test pier model. The stiffness identification is simulated in the completion stage by adding elastic support and concentrated mass on the top of the model pier. The results show that the difference between the identification results of the bare pier and the calculated value of empirical formula is only 2.97%. The error of the identification results obtained by simulating the completion stage is less than 2.34%, and decreases with the increase of the constraint stiffness of the pier top. This method has a high accuracy and is suitable for identifying the vertical restraint stiffness of the foundation of constant section piers of continuous beam bridges.