He regularly suffered physical abuse at Smyllum Park in Lanark, where he and his siblings were taken in 1954.
Mr Docherty went on to found the Care Abuse Survivors (Incas) group 20 years ago.
Alan Draper from Incas was quoted by The Herald in Scotland as saying: "Frank will never be forgotten, not just by his family, but by the many who had joined in the fight and by the hundreds of survivors he gave comfort to over the years by his compassion and the gift of his time which he readily offered.
"Frank was a hero. May he rest in peace."
Smyllum Park is now among a number of sites currently being investigated by the Scottish Child Abuse Inquiry which is due to report its findings in October 2019.
Mr Docherty's death - before the inquiry has concluded - has led to fresh calls for an interim compensation scheme to be introduced for victims.
Mr Draper added: "The current government were finally forced into a Public Inquiry but continue to show a total disregard for the suffering endured by survivors in their refusal to grant interim payments to sick and elderly survivors.
"They need to hang their heads in shame."
A Scottish Government spokesperson told The Herald there would soon be a consultation concerning a potential redress scheme.
They added: "We are deeply saddened to learn of the death of Frank Docherty and our sympathies are with his family.
"This Government has taken unprecedented steps to give a voice, and support to survivors of child abuse in care, including establishing one of the widest-ranging public inquiries that Scotland has ever seen.
"The Scottish Government is committed to consulting with survivor groups and other relevant parties, to fully explore the issue of financial redress."