For the second time this summer, the largest sculpture on Nicollet Mall has been sealed off to discourage a growing number of homeless adults from gathering and sleeping there.

The 10-ton sculpture titled "Nimbus" resembles a curved airplane wing and includes a few rows of amphitheater seating for public performances. The art piece was installed in December on space outside the Minneapolis Central Library between 3rd and 4th streets.

The decision to barricade the space around the sculpture was made by Steve Cramer, president of the Minneapolis Downtown Council and Downtown Improvement District. Cramer said the growing number of homeless people hanging out there during the day and sleeping nearby at night had created safety and sanitary issues.

Cramer has reached out to city officials to find a solution to the problem.

"This is challenging. In effect, this is an encampment," said Cramer. "The reasons to barricade the area were absolutely justified."

As many as 45 homeless people have been seen at the sculpture during the day, and about 15 people sleep there at night, he said.

Many are in the area during the day to take advantage of homeless services and programs at the nearby Central Library. But some are cited for trespassing, for inappropriate behavior or for violating library policy.

The sculpture was initially barricaded in late July. The area needed significant cleaning for health reasons, and graffiti on the sculpture needed to be removed, Cramer said.

Often, the homeless would gather and stay in the area after a play, puppet show or music performance at the sculpture.

The area was again closed off last week for the same reason, as well as to keep the nearby blocks clear while the city works on the mall's planting beds, Cramer said.

Though the barricades will remain in place for six weeks, the homeless will most likely return, he said.

That is why he contacted the Public Works Department, City Council and police to devise a plan to help the homeless into better and safer living situations.

Minneapolis Police Department spokesman John Elder said police know about the problem and are working to help resolve the issue.

Over the past three years, Minnesota has seen a significant increase in the number of homeless people living outside formal shelters.

The homeless population was up 93% in the Twin Cities metro area during that time and up 36% in greater Minnesota, according to a recent study by Wilder Research. Nearly one-third of homeless adults are employed, the study showed.

The area around the sculpture was empty Friday afternoon, with "Do Not Enter For Maintenance" signs hung on the barricades. A 62-year-old homeless man who was standing nearby said he had slept there before.

The man, who asked not to be identified, said he now lives in a shelter and has enough money to move into a more permanent residence in northeast Minneapolis.

"People don't want to stay in shelters during the summer, and they migrate to places like this," he said. "It was a decent place. But people would be stoned or drunk and get into fights. Then the cops would come and shut things down."

The Central Library, which is part of the Hennepin County Library system, serves hundreds of people experiencing homelessness every day, said Amy McNally, library services manager for the Central, Sumner and Golden Valley branches.

The atrium at the Central Library is accessible to the homeless before the building opens for business daily. The library also provides coffee, a craft club and a full-time social worker to connect people with services and housing, McNally said.

"We see the library as a place open to everyone," McNally said. "We see a role to help reduce disparities and help people find housing and employment."

The library has formed a Patrons Experiencing Homelessness Advisory Group to build leadership within the homeless population.

The group advocated opening an atrium early on Sundays because shelters close early in the morning.

The library also shows movies on Sundays, which are regularly attended by more than 200 homeless people, McNally said.

When someone exhibits bad behavior or breaks library policy, however, they will be cited for trespassing, in accordance with state law, she added.

"It's not done very often, and we don't enter into that action lightly," she said, adding it's not always homeless people creating the problems.

Sculptor Tristan Al-Haddad, who lives in Atlanta and created Nimbus, said by phone Friday that he was aware of the problem of the homeless gathering and sleeping near the sculpture. He said all citizens have rights to public spaces and there are some who need help.

"I have compassion for what they are going through," he said.

McNally said the library will miss having access to Nimbus while it is closed. Cramer agreed, saying it is a truly beautiful space.

"It's nice for people to sit and enjoy and be a passerby," he said. "We never anticipated it would be a place where people might hang out all day and night."