A coalition of book merchandisers has joined two Alexandria residents to challenge the constitutionality of a new state law that bans the display of sexually explicit material that, even if not obscene, could be "harmful to juveniles."

In a complaint filed yesterday in Alexandria federal court, the group says the law, passed this year by the Virginia General Assembly, requires them to remove best-sellers by authors such as Sidney Sheldon, Judith Krantz and Harold Robbins from bookstores, supermarkets, convenience stores and airports.

However, many of the offending books would remain available on the shelves of public libraries, they say.

The plaintiffs include the American Booksellers Association, the Association of American Publishers, Council for Periodical Distributors Association, International Periodical Distributors Association and the National Association of College Stores. The others are Books Unlimited in Arlington, Ampersand Books in Alexandria, Amy Bush, a professional counselor who treats emotional and sexual problems, and her 16-year-old daughter Jessica.

They are asking the court to permanently enjoin Alexandria Public Safety Director Charles T. Strobel and Arlington Police Chief William K. Stover, listed as defendants, from enforcing the new measure, which became effective July 1.

They are also asking that the statute be declared unconstitutional as a violation of the First Amendment.

Attorney Robert Plotkin said the plaintiffs are not objecting to Virginia's 1975 law that prohibits the sale or loan to a juvenile of any sexually explicit book, magazine, picture, film, sculpture or sound recording.

Rather, they are challenging the recently passed amendment, which prohibits display of such material "for commercial purpose in a manner whereby juveniles may examine and peruse" it.

The book vendors say they have "no commercially viable means" to comply with the ban. They would have to remove the offending books from their shelves or rope off certain sections of their stores to those under 18 years or refuse entry to juveniles. "Most of the best-sellers I have read in the past year contain references to sexual encounters or sexual conduct that I do not believe are obscene as to adults, nor . . . to more mature teen-agers, such as my daughter, Jessica," said Bush.

"I believe it means we will not be able to display or shelve any book or periodical which contains a narrative description or picture of sexual conduct or nudity," said Carol Johnson, owner of Books Unlimited, Inc. "We would have to remove or butcher at least three areas of specialization: parenting and psychology, fiction and mysteries."

Noting that popular writers of teen novels such as Judy Blume and Norma Klein deal with the subject of sexual conduct, Johnson said the "books are not appropriate for 8-year-olds, but they are indeed appropriate for young people, ages 14 and up."

"If you take it literally, it could reduce material available to people to what is only appropriate to a 10-year-old," said Plotkin. "It's overkill; that's my concern."

He said the new restriction, which also covers "sound recordings," might also force record stores to stop displaying rock music and videos with sexually explicit lyrics.