More than 1500 students, professors, and staff members at Boston University (B.U.) yesterday gathered to show support for faculty, clerical workers and librarians on the second day of their strike.

Anyone on a picket line faces the same struggle, Cesar Chavez, president of the United Farm Workers, told those at the afternoon rally. Chavez is in the Boston area promoting a boycott of United Brands, Inc. products.

Student activists and members of the faculty union also addressed the crowd.

Although the university was officially open for business, most classes did not meet, and many secretaries and librarians did not report for work, Wesley J. Christenson, B.U. director of public relations, said yesterday.

"Classes were very small," Samuel Y. Edgerton, a professor of art history who crossed picket lines, said yesterday. Edgerton added he opposes the strike because it "only hurts the students." About one-third of his students attended his classes, he said.

The faculty union's executive board called the strike Wednesday night after the University's trustees postponed ratification of a contract pending clarification of sections they called unclear.

Robert C. Bergenheim, a member of the board of trustees, said the trustees delayed ratification of the contract because they were not familiar with the exact terms their negotiators had agreed upon, and because they wanted to clarify some issues.

"It was unfortunate and it sure as hell won't happen again," he said, adding. "It was not planned."

Christenson yesterday repeated an earlier warning that negotiations would begin back "on square one" because of the strike. However, Bergenheim disagreed, saying, "The agreement is not jeopardized--we'll begin right where we left off."

Barbara B. Levy, a spokesman for the faculty union, said the faculty "is willing to discuss issues which may be clarified, but reworking terms of the agreement--that's out of the question."

Negotiators will resume bargaining today, and both sides said they could reach an agreement over the weekend