Bridge Engineering Blog & Technical Insights

Earthquake disasters can generate great damage energy, resulting in many buildings and infrastructure being damaged to varying degrees, so it is necessary to implement seismic treatment for structures. The causes of bridge earthquake damage and seismic reinforcement measures are introduced.

It is a passive and negative seismic countermeasure to resist earthquakes by using the structure's own seismic properties (strength, stiffness, ductility). However, control devices (systems) are applied to the structure, and the control devices and structures are jointly subjected to seismic action to tune and mitigate the seismic response of the structure. It is a proactive earthquake countermeasure. The shock isolation design belongs to the latter.

The specifications for the seismic design of bridges in the registration examination mainly include the "Code for Seismic Design of Urban Bridges" CJJ 166-2011 (hereinafter referred to as "City Bridge Resistance Regulations") and the "Code for Seismic Design of Highway Bridges" JTGT2231-01-2020 (hereinafter referred to as "Public Bridge Resistance Regulations"). Railway engineering seismic design specificationsGB 50111-2006 (2009 Edition). Purely from the perspective of review and preparation, you only need to master the "City Bridge Anti-Regulation" and "Public Bridge Anti-Regulation". There are questions about bridge earthquake resistance every year, and the test questions in recent years are as follows:

The correct name for this large golden ball resembling a single pendulum inside 101 is the tuning mass damper (Tuned mass damper, referred to as TMD). The function of this damper is mainly to mitigate the vibration comfort problem caused by strong winds in the upper part of the building (related to the peak acceleration of the floor and not related to the floor displacement). According to relevant studies, when the floor acceleration reaches 50mm/s^2, some people will begin to feel the swing of the building and feel uncomfortable. Therefore, Taiwanese regulations stipulate that under the action of wind force during the return period of half a year (which occurs twice a year), the peak acceleration response of the top floor of the building shall not exceed 50mm/s^2.

Eddy current tuned mass damperIt is a product developed on the basis of ordinary tuning mass dampers, and its working principle is to use the mass system to cut the magnetic induction wire to form an eddy current, which is converted from kinetic energy to heat energy dissipation to produce a damping effect. The most famous of them isShanghai TowerEddy current tuned mass dampers weighing up to 1,000 tons are used. So what are the advantages of eddy current tuning mass dampers compared with conventional tuning mass dampers?