So there is some debate about this.

Older ideas basically stated that Charles the Bald's bridge building activities were directly responsible for a decline in Viking Activity. It was thought that he built quite a few bridges along the Seine and Loire.

We certainly have direct references in the sources to this activity, including detailed discussion of how workers were levied to complete at least one bridge.

In 862 the Annals of Saint-Bertin one of the major sources for Frankish history in this period states that "[Charles the Bald] followed some indispensable advice and rebuilt the bridge across to the island by Trillbardou, thereby cutting the Northmen's access to the way down the river. He also assigned squadrons to guard both banks of the Marne [a tributary of the Seine]. The Northmen, now tightly hemmed in by these moves, gave hostages chosen by Charles, and on his orders: the conditions were that they should return without any delay all the captives they had taken since sailing up the Marne, and either, on some prearranged assembly-date, should withdraw from the Seine with the other Northmen, and seek the open sea, or, if the others would not withdraw with them, [they] should unite with Charles's army to attack those who refused to go."

So we can see that bridge building could be affective at preventing movement up river and could be used to force Northmen to withdraw. Note the lack of battle. It turns out that Vikings and Franks were both typically unwilling to fight pitched, equal battles. They liked overwhelming odds of victory and whenever we see moments where things might be unbalanced we tend to see deals, hostage exchanges etc.

Later that same year we are told that "Charles caused all the leading men of his realm to assemblr about 1 June with many workmen and carts, at the place called Pîtres, where the Andelle from one side and the Eure from the other flow into the Seine. By constructing fortifications on the Seine, he closed it off to ships sailing up and down the river. This was done because of the Northmen."^1

We see similar discussion of bridge building in 865.

So, we know that there was an active bridge-building campaign in the 860s designed to halt Viking incursion. The real question is whether it was a sustained effort, and just how big it really was. All we actually hear about is Pitres and the area around the Marne (although there are other passing references elsewhere I believe).

The bridges were originally thought to be large stone affairs but this has been re-evaluated and they were probably less permanent constructions with a few notable exceptions.

Simon Coupland, one of the major scholars who works on Viking activity in Francia has argued pretty convincingly that older estimates of the number and use of bridges has been over stated. The article you want to read is, appropriately enough, called "The Fortified Bridges of Charles the Bald" in The Journal of Medieval History Volume 17, Issue 1, 1991 pp. 1-12.

He points out that permanently blocking the Seine would have been untenable, both from a strategic and economic point of view. He also notes that the lull in activity in the 870s is quickly replaced by very active Viking raiding and even full-scale invasion in the following decades. So either the bridges fell into disrepair again or were taken down or destroyed.

Anyway, check out the article if you can, I think it will do a great job of answering your questions more deeply.

As to major battles and sieges. The siege of Paris in 885 is quite major, and involved a lot of fighting over bridges and fortifications. English translations of a poem by Abbo of Saint-German are available and while not entirely realistic it certainly give a sense of the layout of the long-lasting conflict.

1: This translation is from Janet Nelson's translation of The Annals of St-Bertin Manchester University Press 1991. You can get it fairly cheap if you want to read them yourself. The Annals of Fulda and Regino of Prüm's Chronicle are also available in translation from Manchester and provide even more examples of Franco-Scandinavian conflict and interaction.