The Tacoma Narrows Bridge collapse : The Tacoma Narrows Bridge became famous for its dramaticwind-induced structural collapse in 1940, It is one of the most well-known cases of structural collapseandsignalled the need for a rigorous aerodynamic design of long bridges.Photos available here (select "View all items" or a specificcategory in the drop-downmenu). Videos available onYouTube: Video I.

Water Isolation using geosynthetics for a two sub-storey parking in Patras (September 2000)

The photos are from a project in the city of Patras, Greece. The project consists of a two sub-storey parking below an entertainment complex. After the completion of the deep excavation, geosynthetics were used for the water isolation of the excavated area. The Geomembranes used (yellow color), are bonded together with some kind of glue. It is very important that the two parts are perfectly bonded using thermal bonding. This is a very delicate procedure since imperfections in the bonding could lead to water intrusion. Photos of the thermal bonding procedure are provided. Below are briefly described some details in the execution of thermal bonding and Construction Quality Assurance (CQA).

Methods to check the quality of work

There is a very thin copper wire along the joining. This wire must not have contact with the air if the work is done properly. So at the two-ends of the wire a source (like a battery) is installed. If there is a pointwere the wire comes in contact with air, then a sparkle comes out and the spot is indicated to restore it.

A pump presses air between the bonds. If the air pressure falls, this mean that in a place the textiles are not bonded perfectly.

Materials

In the specific site, three kind of geosynthetics were used (check the photo above) forming a "geocomposite":

In the outside, in contact with the concrete a tough plastic was used for the protection of the other two PVC (dark green) typically called Geoglass.

In the middle, a white colored geotextile (Polyfond type) is used to protect the geomembrane.

On the top, a geomembrane (yellow) is used as a hydraulic barrier.

Bonds with heat of the textiles

Views of the Site

Reference:

More information on the project of the deep excavation using slurry walls, are provided here.

This is a picture of a bridge in Andros. The drawing, made in 1840, is of a British traveller. Even though he presumed that the bridge was constructed by the Franks, it seems to be much older, of the 17th century.

The main span of the bridge is 7650ft (2331.7m). The diameter of one cable is 92.4cm and in each cable there are 27572 wires! Total wire used is 80,000 miles (128,748m) and the weight of each cable is 24500 tons (22.226m.tons).

Figure 1: View of the bridge pier, currently under construction, that is currently floating near the coast. Access to the pier is through the ship illustrated in the figure. The ship is modified to allow transportation of the reinforcements using trucks.

Figure 2: Another pier of the bridge.

Figure 3: Reinforcement placement in the pier, according to the design. The reinforcement has previously being transported with a truck next to the pier.

Figure 4: Interior of the pier of Figure 6. The thickness of the reinforced wall is approximately 2.0m.

Figure 5: Interior of the pier. Detail of the pier wall.

Figure 6: View of the piers that are under construction close to the coasts. The right one is the one illustrated in Figure 4 and 5.

Figure 7: View of a pier that has currently touched the bottom of the sea.

Figure 8: Footing of a pier, currently under construction, in the dry dock.

Figure 9: Footing of a pier, currently under construction, in the dry dock.

Machine used to automate the shaping of the reinforcements in the shape required by the design.

Machine used to automate the shaping of the reinforcements in the shape required by the design. Used for steel rods of smaller diameter. The user has specified the geometric characteristics of the steel rod. On the left you can see the steel rod which is inserted in the machine to be shaped.

Steel rods to be used in the above machines. A label with the barcode described the technical characteristics of the reinforcement that are going to be used to.