Brigham and Women’s Hospital started returning to its regular routine on Monday, a day of relief tinged with lingering bitterness, after a threatened nurses strike was averted over the weekend.

The Boston hospital is admitting patients, ramping up surgeries, and rescheduling canceled appointments now that a tentative new contract with the Massachusetts Nurses Association has been hammered out.

“Brigham and Women’s Hospital is open for business as usual,’’ Dr. Ron M. Walls, Brigham’s chief operating officer, said at a lunchtime news conference, as employees in scrubs took advantage of the summer weather to eat on a lawn nearby.

The hospital, one of the busiest in the state, had been bracing for a walkout on Monday morning by 3,300 nurses. Instead, nurses walked into the hospital en masse for the morning shift, hugging and smiling. At the press conference, hospital officials lauded the contract deal and declared that Brigham operations would be back to normal by Friday.

Dr. Elizabeth G. Nabel, Brigham’s chief executive, thanked negotiators from the union for bargaining in good faith, striking a markedly different tone from just a few days ago, when she said she doubted whether the union truly wanted to reach a deal and avoid a job action.

A walkout by nurses would have been the first ever at Brigham and the first in Boston in 30 years.

Brigham officials said they were beginning “the healing process.’’

“We’ve been challenged in the past few years, between the Boston Marathon bombing and the tragic killing of Dr. Michael Davidson, and each time we have . . . come back stronger, and I fully anticipate we will come back stronger again,’’ said Nabel.

Davidson was killed in a shooting at the hospital last year. That event led the nurses union to negotiate stronger security policies as part of their contract with the hospital.

The contract also resolves previous disagreements on wages, health benefits, staffing, and the use of new patient-monitoring devices.

Laurie Demeule, a member of the nurses’ bargaining committee, arrived at work Monday beaming and sporting her union pin.

“We walked in all together first thing this morning. It was awesome,’’ she said.

But Demeule said it would take time to fully repair the rift between the union and the hospital. “There’s a lot of healing to go,’’ she said.

Negotiators from both sides worked over the weekend to reach an eleventh-hour compromise, aided by elected officials, including Mayor Martin J. Walsh, who made dozens of phone calls to encourage both sides to find common ground. Businessman Jack Connors, a former chairman of Brigham’s parent company, Partners HealthCare, also advised hospital officials through the weekend.

“Both sides were able to sit down at the table, put aside their feelings, and come up with a contract that’s good for both sides,’’ said Walsh, a former labor union leader.

Brigham, through a “command center’’ established earlier this month, had reduced operations at the hospital to 60 percent of normal to prepare for a potential strike. There were 360 patients at Brigham on Monday, hundreds fewer than are typically at the 793-bed hospital. Officials said they are readmitting patients who were transferred, including babies from the newborn intensive care unit.

Brigham paid a staffing agency to hire 700 temporary nurses who were scheduled to help care for patients in case of a strike, but the temp workers were not needed after the contract compromise was reached. Officials have not said how much the strike preparations have cost them, except that it is in the millions of dollars.

Priyanka Dayal McCluskey can be reached at priyanka.mccluskey@globe.com. Follow her on Twitter @priyanka_dayal.