Captain reported severe turbulence resulted in a failure of the autopilot. After landing; appropriate maintenance entries were made in the aircraft log book.

Narrative

While approaching ZZZ on the arrival we were advised of moderate turbulence in the vicinity of ZZZZZ. We were cleared to cross ZZZZZ at FL190 and 250 knots. Immediately after we were advised about the turbulence I communicated this to the Flight Attendants and told them to secure the cabin at this time. Minutes later while approaching the ZZZZZ intersection the aircraft encountered severe turbulence which lasted between 30 and 60 seconds. Immediately upon entering the turbulence I took control of the aircraft and at the same time Auto Pilot disconnected itself. I then endeavored to maintain a steady attitude and reduce the constant changes in pitch and roll that were being encountered. At no time did ATC note any altitudes deviations.Once the aircraft was in VMC conditions the turbulence dissipated and we noted several caution messages on the EICAS. These included: AP FAIL SPOILER FAULT ELEVATOR FAULT RUDDER FAULT. I maintained aircraft control and also assumed control of communications while the First Officer then began the process of running the associated checklists from the QRH. I contacted the Flight Attendants to check on the status of the cabin. No injuries were reported and all passengers were seated at the time of the incident. The Flight Attendants were in the forward galley and also uninjured. I reported the turbulence and system failures to ATC and elected to continue with vectors to ZZZ. I also requested an extended final for Runway XR in order to complete checklist items. The EICAS Messages were cleared and we configured the aircraft for a normal landing. Upon landing we checked with the Flight Attendants who again reported no injuries. At the termination of the flight; FLT CTRL NO DISPATCH appeared on the EICAS. The parking checklist was completed and the turbulence encounter and all EICAS Messages were entered into the logbook.