The Democratic National Committee broke ground Tuesday for a new national headquarters building on the northeast corner of Canal and Ivy Sts. SE on Capitol Hill. The committee now uses leased office space at 1625 Massachusetts Ave. NW and expects to save some $500,000 a year in rent by moving. When the $6 million, four-story building is finished in mid-1984, its 42,000 square feet of space also will house the House Democratic Congressional Committee and the Senate Democratic Campaign Committee.

DNC officials say the building will be equiped with state-of-the-art computer fund-raising equipment, a media center enabling Democrats to use satellite television transmissions and teleconferences, and a research library with computer links to state Democratic offices.

Charles Manatt, the DNC chairman, said the construction is "symbolic of the resurgence" of the party because "we have been siphoning off too much good money for rent and duplicative services that could be better used for party building activities and for our Democratic candidates."

The building has been designed by CHK Architects and Planners of Silver Spring. The architects said the precast-concerete-and-glass building, with its balconies, metal railings, mansard roof and brick-paved sidewalks, was designed to harmonize with nearby offices.