LTV Corp.'s bankruptcy reorganization petition yesterday came as no surprise to those who have been following the longtime decline of the domestic steel business.

"It's hardly a shocker," said Robert W. Crandall, a senior fellow at the Brookings Institution, an economics and political research group in Washington.

Depressed prices, shrinking demand, vulnerability to imports and other ills have plagued the U.S. steel industry for so long that another bankruptcy filing by a major steel maker "was widely expected," Crandall said.

LTV, which is based in Dallas, is the nation's second-largest steel maker. It now joins 9th-ranked Wheeling-Pittsburgh Steel Co., based in Pittsburgh, in Chapter 11 bankruptcy proceedings. Wheeling-Pittsburgh filed its bankruptcy petition last year. Under Chapter 11 of the bankruptcy law, companies continue to operate while working with the court to pay off their creditors.

The LTV filing "doesn't come as a surprise to me," said the Rev. William Hogan, a priest and industrial economist at Fordham University in New York. "There has been a depression in the domestic steel industry for the last three years. Things have been difficult," Hogan said.

Actually, the hard times for Big Steel have lasted longer than that. Domestic steel companies have closed down or authorized the shutdown of almost 700 steel-manufacturing and related facilities since 1974, according to figures compiled last month by the American Iron and Steel Institute in Washington.

Seven steel companies have gone out of business during that time, and 18 others were sold "in whole or in part" to other companies, sometimes as the result of bankruptcy proceedings, the AISI report said.

By any measure, steel employment has dropped dramatically. The United Steelworkers of America lost nearly half its 1.4 million members in the past decade, the steepest decline ever recorded by a union. But that figure obscures the true condition of steel employment, because many steelworkers union members do not make steel.

The steelworkers union long ago decided to mimic the diversification of some of the nation's biggest steel makers, who increasingly saw steel production as a losing business. The companies made forays into the oil business and other non-steel areas, and the union sought new members in offices and at chemical manufacturing companies instead of at steel plants.

The average number of hourly workers in steel production and shipment was 150,900 last year, compared with 170,700 in 1984 and in contrast to a historic high of 544,300 hourly steelworkers in 1953.

At LTV, there are an estimated 30,000 USWA-represented workers, including about 4,000 already on long-term layoff. In addition, some 61,000 retired LTV employes are receiving pension benefits.

The company's financial obligations to USWA employes and pensioners make the union the largest single creditor in the bankruptcy proceedings, USWA officials said yesterday.

"We will do everything in our power to protect our members' rights under the collective bargaining agreement" ratified last April 4, said USWA President Lynn Williams.

LTV's difficulties underscore "the contention that our union has been making the past few years" about the negative effect of imports on the health of the domestic steel industry, Williams said.

Steel industry analysts said that the union has a point, one poignantly illustrated by the industry's frustrating battle to get the kinds of prices it needs to offset costs.

In the United States, the typical integrated steel mill's pretax costs were down 23 percent in 1985 -- to $473 per net ton, versus $611 per net ton in 1982.

The steel companies were operating at 70 percent of capacity in 1985, compared with a rate of 55 percent of capacity three years earlier.

But domestic steel companies continued to lose money despite those improvements in efficiency. Imports, which accounted for 22.6 percent of the American steel market for the first five months of 1986, have helped to drive domestic steel prices $15 per ton lower than the cost of production, analysts said. Depressed consumption of raw-steel and finished-steel products also is holding prices down, analysts said.

Depressed consumption means shrinking capacity. For example, the domestic steel industry was capable of producing 160 million tons of raw steel in 1977, but is able to roll out 127.9 million today. More shrinkage is needed for the industry to regain fiscal health, Crandall, Hogan and other analysts said.

Meanwhile, other domestic steel makers are viewing the LTV stituation with concern. Chief among those is Bethlehem Steel Corp., the nation's third-largest steel manufacturer, whose stock price dropped a point to 12 1/8 yesterday on the news of LTV's reorganization filing.

The LTV filing "is a clear indication of the major difficulties faced by basic industry in this country, and it should be of concern to all Americans," a Bethlehem Steel spokesman said. The spokesman said, "It is difficult at this point to assess the impact of the filing on the steel industry."

However, Bethlehem Steel, which lost $92 million in the first quarter this year, "has no plan to take a similar course of action," the spokesman said.

Bethlehem Steel recently received $263 million from the sale of several assets, the spokesman said.