forces in motion
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Bridges under seismic stress

MAURER expansion joints can be designed so that the seismic displacements are completely absorbed with a modular expansion joint, or the expansion joints are designed with a fuse box system for extremely large seismic movements. Both variants prevent significant damage and the structure can at least be accessed by emergency forces after an earthquake.

Fuse box system for road bridges

Fuse Box System in longitudinal direction, Type I and II

When large seismic closing displacements occur, leading to full closure of the joint and contact between all centre beams, the fuse box system is triggered to prevent the expansion joint from being crushed between the bridge deck and the abutment or transition pillar.

Type I:

When major closing movements occur, one side of the expansion joint is pushed upwards by an inclined steel ramp. The safety mechanism is activated by the intentional failure of certain welds at defined locations.

Type II:

In case the closing movement is too great, the expansion joint on one side drops down into a space prepared in the fuse box. There it can perform movements that exceed the maximum closing movement. The locking mechanism is activated by intentional failure of the bolted connections near the road surface and at the bottom of the joint where it connects to the structure. This type of fuse reduces damage to the road surface and allows better drive-over capability in the triggered position. During aftershocks, normal movement capacity within the expansion joint is guaranteed.

Fuse beam

Type III:

In the event of an extraordinary closing movement, predetermined breaking points or defined welds on the “fixed” centre beams break. This means that the centre beams on the support bar can absorb further movements. Then the expansion joint can be driven over the regular displacement capacity.

Fuse box system in transverse direction

Type IV:

As soon as the bridge movements in the transverse direction exceed the movement capacities of the joint, a sliding guide system is activated by the failure of a notched steel pin. This allows the entire joint to move laterally without damaging any of its structural elements.

++++ very good +++ good ++ limited + very limited
MAURER ex-pansion joint Guided cross-tie MSM® swivel joist expansion joints without fuse box MSM® swivel joist expansion joints with fuse box Type I MSM® swivel joist expan-sion joints with fuse box Type II MSM® swivel joist expan-sion joints with fuse box Type III Girder grid expansion joints with fuse beam Type IV
Bridge type Railway Road Road Road Road Road
Traffic safety during an earthquake ++++ ++++ ++ +++ +++ ++++
Condition after DBE ++++ ++++ +++ ++++ ++++ ++++
Condition after MCE ++++ ++++ ++ +++ +++ ++++
Crossing for rescue vehicles after earth-quake DBE, MCE ++++ ++++ ++ +++ +++ +++
Repair effort none none Medium-significant medium medium medium