Viktor's Barrage actually spawns explosions on the ground instead of dropping them from above. Moving backwards while he is locked on to you will make them hit your shield if you get the center of the blast off you and in front of your shield.
His ultimate will completely ignore shields (Including Barik's ultimate) and instead will instead do direct health damage. Find a blindspot instead of trying to tank the damage as a frontline champion.
As a frontliner, try to bait out Recharge by using secondary shield abilities (i.e Safe Travel, Bowling Ball, Protection ) and activate your main shield after his ability ends to avoid him siphoning it.