Building the Ravenel Bridge

March 8, 2005 Aligning edge girders, pinning and then bolting splice plates

It was windy but it happened. After the front passed, jacks and counterweights were used to align the ends of the east and west decks. Here is the before (about 2:30pm). Note that none of the bolts have been inserted in the right side of the top, vertical and blottom splice plates.

These iron guys are waiting for alignment of the holes in the splice plate with the holes in the 216 edge girder. The light passing through the bolt holes provides a measure of the quality of alignment. On the left is the alignment of the south splice plate and on the right is the alignment of the north splice plate.

First, the tops of the edge girders are aligned, the top splice plate is then pinned to the edge girder and then bolted in place. Here is a little bolting action.

Here is Lewis (bottom) Jack (top) and someone else (?) encouraging the north end to behave itself. Left (before) and Right (after)

Being an iron worker is something else. Jack's acrobatic skills are quite useful.

So you are probably thinking - how do you adjust the vertical and horizontal alignment? I watched today and was quite surprise. For horizontal alignment, hydraulic jacks are used to nudge the deck forward. Vertical alignment is an exercise in free body diagrams. Fork lifts are used - either with or without counterweights. They are moved closer to the gap or further away from the gap - depending on whether you need down or up adjustments. Tomorrow I'll have some photos of the jack and the fork lifts. Here is the mobile counterweight on the west deck: Initial position

After moving back toward the west pylon

Here is the mobile counterweight on the east deck: Initial position (left) and after moving back toward the east pylon (right)

Horizontal alignment is encouraged with these jacks - that press against a rather large concrete block and frame tied to the deck. Here is shown the jack before applying hydraulic pressure (left) and after Wilbur Poole applies turns on the hydraulic pressure which moves the inner cylinder about 2 inches (right)

To make the jacks do their thing, Wilbur has to switch the pump on, increasing the pressure in the lines and forcing the jack cylinder out. To put some size scale - the right photo shows the jack relative to Wilbur's gloved hand while the right photo shows the team. Peo Halvarsson (left of kneeling Wilbur) is doing his usual bit of encouragement

The hydraulic jacks do their job and here is the result (about 5:00pm). Note bolts now fill the top splice place and drift pins are holding the vertical splice place in position and the first bolts have been inserted.

A last look at the closed gap

March 10, 2005 Two days later, bolting the north and south splice plates is complete