With the gleaming marble of the Lincoln Memorial as a solemn backdrop and bouquets of red, white and blue fireworks splashing across the pitch-black sky, President-elect Ronald Reagan waved and smiled to a shivering mass of 15,000 people last night at opening ceremonies for his inauguration.

Reagan chose not to address the enthusiastic crowd, which cheered repeatedly during the extravagantly choreographed fireworks and laser light show and harmonized with the Mormon Tabernacle Choir's renditions of "God Bless America" and the "Battle Hymn of the Republic."

But the man who will become president at noon Tuesday did step to the front of an enormous blue-and-white podium built in the shape of an eagle and acknowledge cheers of "We love Ronnie."

The ceremony, kicking off what has been billed as the "biggest and best" inauguration ever, was marred by tragedy earlier in the day when a five-story scaffold supporting a fireworks display collapsed hours before Reagan's appearance. Michael Kelpy, a 65-year-old College Park man working on the scaffold at the time, was killed and another man was injured.

The scaffolding was to have been part of an elaborate pyrotechnic portrait depicting the inaugural seal. It and another 50-foot portrait depicting Reagan and Vice President-elect George Bush were to have been part of the grand finale last night. After the accident, officials decided to cancel both displays.

The wind did not hamper the display of hundreds of the rainbow-colored fireworks and emerald green laser lights that danced into the night sky with the precision of a Busby Berkeley routine from the Hollywood of days gone by.

The laser lights formed an illuminated ribbon linking each of the national symbols -- the Washington Monument, Capitol, White House, Jefferson Memorial and Lincoln Memorial.

The dramatic display brought "oohs" and "shhs" from the crowd and drew comments such as "truly fabulous" from a laser scientist watching the show with his 6- and 7-year old daughters.

Master of ceremonies Efrem Zimbalist Jr., former star of "The FBI" television series, quoted excerpts from Reagan's acceptance speech at the Republican National Convention and praised the president-elect for "reawakening national pride."

The 300-member Mormon Tabernacle Choir, wearing matching plaid mufflers atop a potpourri of coats, sang, and the U.S. Army band played Aaron Copland's "Fanfare for the Common Man" and John Philip Sousa's "Stars and Stripes Forever." A coatless man stood in the subfreezing night while captioning the entire event for the deaf.

Many in the crowd kept warm by marching patriotically in place and, despite the weather, most interviewed said they had come because the evening was a piece of history.

"A frozen piece, maybe," one man said, "but still a piece." Temperatures hovered around 25 degrees, but a bitter wind pushed the chill factor below zero. Still, 15,000 gathered around the Memorial, and another 15,000 were along the mall, according to U.S. Park Police estimates.

Mary Kay Finley of Washington, who said she was "one of those disgruntled federal workers that didn't care for Mr. Carter," stood near the mouth of the reflecting pool watching orange, white and pink flares and sparklers erupt from the pool like glittering lava.

"That's fabulous," she exclaimed. "I think it's better than the Fourth of July."

Closer to the front of the crowd, 72-year-old Miriam Rosenberg sat swaddled in several layers of clothing and blankets, watching the show on a portable television set in her lap.

Describing herself as "one of the staunchest Republicans around," she said she had come up from Miami to visit her grandchildren and to see the inauguration, "and because it just may be the last big thrill of my life."

The orderly crowd booed only once -- when D.C. Mayer Marion Barry was introduced -- and most of its comments showed affection for Reagan and pride in the pageantry that is part of the American system.

"It's great, just great," said Rachel Adams, a school teacher from Idaho, adding that she hoped "those two great Americans don't get too cold up there." It seemed unlikely as Reagan, wearing a heavy blue wool coat, white gloves and light grey scarf, and his wife Nancy, swathed in fur, sat on stage with blankets on their laps.

As the ceremony ended in a five-minute blaze of fireworks, a small child shouted, "Good luck, Mr. President," and a deeply tanned middle-aged man, thinking perhaps of Reagan's Hollywood background, slapped his knee and shouted, "That's a print."

The televised 45-minute grand opening was designed to set a dramatic pace for four days of round-the-clock inaugural extravaganzas that will make the 40th president's inauguration the most elaborate and expensive ever undertaken.

The inauguration is also the first subsidized by taxpayers through an unusual inaugural trust established by Reagan's committee. The trust is designed to attract tax-deductible contributions and raise an estimated $1.5 million.

Contributions are tax-deductible, according to inaugural attorney Roger Clark, because contribution to the trust can be used for scholorships that will be given to needy students interested in government.

However, trust money also can be used to finance public events where no admission price is charged, Clark said. The committee would not say how much money it has raised for the trust, but sources said the figure was close to $1.4 million.

Nearly all of it, they said, has been earmarked for building $650,000 worth of parade reviewing stands for Reagan and the media and to pay for $160,000 worth of fireworks for Tuesday's final Sky Salute.

Clark said yesterday that the scholarships will be funded after inaugural committee bills are paid.

Originally, officials said Reagan's inauguration would cost an estimated $8 million, compared to $3.5 million spent by President Carter. Now, there are reports that costs could soar to $11 million.

Regardless of the amount, committee officials believe they can pay their bills by selling Reagan souvenirs and inaugural tickets.

"No one has ever tried to put on so many spectacular events," Clark said. "We wanted a cushion."

Despite the high cost of the inauguration and weeks of planning, inauguration visitors were confronted with many last-minute problems. There were a mishmash of problems at Union Station, where voluntees are dispensing 200,000 tickets.

Mix-ups and confusion were so bad that Reagan, was quoted by outgoing Republican Party Chairman Bill Brock as saying, "Next time, maybe the loser should be sentenced to the inaugural."

Alan and Susan Hoffman of Grenada Hills, Calif., ordered tickets for all of the priciest and highest-status events -- the Kennedy Center Ball, the Distinguished Ladies Recedption -- and discovered on their arrival at Union Station that the tickets, for which they spent almost $1,000 were nowhere to be found.

Hoffman was philosophical about the situation as he and his wife munched on gourmet seafood from the Anthony's Pier 4 Restaurant booth at the "Taste of America" food sampling for Union Station visitors.

"I was reading in the L. A. Times last week about this Taste of America thing and how it's supposed to pacify irate ticket holders," he said, as he popped a cold clam into his mouth. "They've done their job. This is delicious.

"You know, we spent about $5,000 to come out here when you count the hotel, the new clothes, the tickets and all, but I wouldn't change a thing. After all, this is history. I don't think the tickets are lost for good anyway. The only thing that really bothered me was a guy from Springfield (Va.) who was complaining to the ticket lady about how far he'd driven. Can you imagine?"

One airline at National Airport lost several Californians' luggage, but at other points, the Louis Vuitton bags were coming off a Pan Am flight from the West Coast by the truckload, as one woman, wearing a thin cotton dress and sandals, inquired about the "nicest place" to buy a fur coat -- fast.

A reporter interviewing ticket officials Friday said an Air Force corporal wandered into the director's office and said he had been dispatched from Fort McNair to pick up tickets earmarked for the first family's guests.

"They're not here," he said, bewildered. "They told me that they're not here!"

A handful of congressmen, including 8th District Virginia Republican Rep. Stanford E. Parris, also were having problems geting tickets.

"This is a nightmare," said a disgruntled Parris. "This is a real mismanagement problem."

An aid to a California congressman said his office had been swamped with calls from angry constitutents who either did not get tickets or wanted to go to other balls.

Despite the problems, greeters, wearing Reagan-Bush buttons, manned 24 hospitality booths at Washington airports and major hotels yesterday where tired but excited inaugural travelers were given free maps, inaugural programs and handfuls of jelly beans, some of the 3-l/2 tons of Reagan's favorite candy donated by a California company.

At National Airport, extra skycaps worked through a maze of baggage. Car rental booths, which usually rent 90 cars on Saturdays, had reservations for more than 400 vehicles.

"The travelers want the full- to mid-size cars," one reservationist explained."Grant Prix are popular; so are Cutlasses, LTDs with landau roofs. Most of all, they want American cars and seem to be really adamant about getting them."

Committee officials said yesterday that ball tickets to the Kennedy Center had been oversold. For a while, they considered creating a 10th inaugural ball to handle the overflow but later dropped that idea.