Johnson played right tackle with the second-team line.
Eagles head coach Doug Pederson said he was confident the team could manage without Johnson.
“I look back to our days in Kansas City,” said Pederson, a former Chiefs offensive coordinator. “We had a lot of injuries there and we were moving guys around, and we had a young left tackle early on. We made it work.
“I'm looking for five tough, dirty, nasty guys that want to go out and just play football. I don't care which five it is, but we're going to find the best five and the right five, and I feel like we've got them here on the team.”
Barbre, 32, started all 16 games at left guard last season. Before that, he was a backup at multiple positions. He started one game at right tackle in 2014. In 2009, as a member of the Green Bay Packers, Barbre started seven games at right tackle.
“I’m definitely going to approach it the same,” Barbre said. “My approach is just to go out and work hard every day, put my best foot forward. I’m going to give it my best, whether it’s one game, four games or 16 games.”
In 2014, Johnson was suspended for four games for violating the NFL performance-enhancing drug policy. Former head coach Chip Kelly had Johnson practice with the second team during training camp, while his potential replacements -- including Barbre and Andrew Gardner -- worked with the first team.
That is what Pederson appears to be doing this time. Johnson faces a 10-game suspension for a second offense.
“I think it would behoove me to have a plan,” Pederson said. “Again, it just goes back to giving these guys an opportunity to get them on tape, to make the corrections now so that down the road, we're prepared for it.
“I wanted to see guys at different spots. What happens if Jason Peters goes down during the regular season, or Jason Kelce goes down during the regular season? I just want to see different guys at those spots. In order to do that, you've got to take time now this week in camp to get that accomplished.”
Seumalo was promoted two days after making his NFL debut in the Eagles’ preseason opener. He was not happy with his performance Thursday night.
“The game wasn’t great,” Seumalo said. “I just started overthinking stuff. When you do that, you play slow. You can’t do that in the NFL.”
Pederson said he has been impressed with the rookie throughout camp.
“A guy that knows his assignments,” Pederson said. “He had a couple of penalties in there, some false starts and things. He's just got to listen to the count. The quarterback cadence was a little different.
“He's a guy that's really challenging to play. He's a young guy that, again, knows his assignments, good fundamentally, a technician. Just, again, I want to put him in positions where he can be successful and help us down the road.”