Forty-two demonstrators protesting nuclear weapons development were arrested in two separate incidents yesterday at the Pentagon after they chained themselves in doorways and spattered blood on columns and walls of the building.

They were among about 200 protesters participating in the second day of a two-day demonstration in the Pentagon's concourse mall.

Those arrested were charged with destruction of government property and failure to obey Federal Protective Service officers, and were later released on their own recognizance.

Twelve of the 42 were arrested early yesterday morning after shackling themselves to the building and thowing blood on the Defense Department headquarters.

But most were arrested shortly after noon when they staged a "die-in," a mock enactment of a unclear war in which the protesters staggered about, squirted containers of blood on the ceiling and walls of the concourse mall, and finally dropped to the floor.

When about 30 of the protesters refused to move they were dragged by police into a line and turned over, and their hands were shackled behind their backs with plastic handcuffs.

No one resisted arrest and there were no reported injuries. A brief scuffle broke out when two of the protesters threw blood against the walls, but the two were quickly controlled by police.

The demonstration against nuclear weapons has become almost an annual event at the Pentagon and there is even a certain rapport between police officers and demonstrators, many of whom have gotten to know each other by name.

Several of the protesters have been arrested at past demonstrations. But for Allen Brenneman, 34, an Elkhart, Ind., mechanical engineer who lay face down on the cold concourse floor, his hands bound behind his back, it was the first time. His daughter, Stephanie, 12, looked on, her glasses spattered with blood that had been tossed earlier.

"I'm scared, but I understand why he did it," she told a reporter.

At the Pentagon's Woodward/Lothrop department store, shoppears and employes pressed their faces against the glass to watch the demonstration.

"It's disgraceful. They ought to lock every one of them up," said Mary Dawson, a store employe.

Maj. Mathew Parrilli, 35, of Fairfax said the demonstrators "appeared to behave themselves and didn't bother anyone. They have a right to think as they do."