The Washington Convention Center, alias Eisenhower Arena, may bring the city all the economic blessings claimed for it.

But an architectural blessing it is not.

The main problem is scale. A subsidiary problem is a singular lack of flair, creativity, wit, inspiration, imagination and sophistication -- to say nothing of genius -- in the design of this $98.7 million megastructure.

The thing is not even ugly. It is just there, bland and massive like a dead whale on a boardwalk.

Rather, it will be there -- sometime in 1982. Work on the site begins next month. A ceremonious groundbreaking is scheduled for April.

For 10 years, after the city lost its proposed Eisenhower Arena to Prince George's County (where they call it "Capital Centre"), city hall pleaded and hassled, mostly with the Senate District Committee, to be allowed to build the kind of civic exhibition and meeting space for big conventions, trade shows and local mass-audience extravaganzas that every red-blooded American city thinks it ought to have.

We finally got it, with slight changes in the originally proposed size, cost and location. The design is all set.

It is thus academic to ask whether good, or at least better, architecture is possible for this kind of conventional convention center, and whether bad architecture will also to turn out to be bad economics.

The conventional convention center trade associations and professional organizations are said to crave, is a flexible structure that accommodates miles of exhibit space for books, fancy food, machinery and whatnot as well as events that seat 12,000 people as easily as a few hundred.

For city officials, the ideal conventional convention center is in or very close to the old central business district. The theory is that conventiongoers walk to their hotels, sprinkling bread along their paths like Hansel and Gretel.

The design for the Washington Convention Center by Welton Becket Associates, Gray and West, and H. D. Nottingham, meets the presumed demand for size with a megastructure of more than nine acres, about 70 feet high. The ground level holds the lobby, meeting rooms, offices, a restaurant and parking space for 250 cars.

The second level is divided into three halls of varying sizes and heights, which can be used together or separately. It also contains the loading docks for bringing in exhibits.

These interior functions are expressed in the exterior configuration of the building, but with little varition, conviction or drama.

The huge boxes jut in and jut out and are sliced off diagonally at the corners. There are ribbons of glass along parts of the structure. The enormous, flat roof expanse is enlivened only by nine neatly lined up penthouse boxes. For further relief, the western exhibition hall shows the outer fringes of its steel truss system, somewhat like a slip showing.

But having thus tried to shake up their monolith a little, the architects wrap it tightly again in a montonous concrete: panel facade. The total effect of the architects' model is that of a giant manufacturing plant such as you see all along America's highways. At 55 m.p.h. it's not too bad but from the pedestrian perspective it is depressing -- particularly five blocks from the White House.

Better architects, however, might easily have done worse.

A more interesting, more graceful and pleasing building of the same size would only call more attention to the fact that the fabric of the city is brutally disrupted, that the harmonious and human pattern of city blocks is literally busted. A well-designed blockbuster is still a blockbuster.

This is not to say we cannot have large convention and exhibit halls. It happen that the first and, in my view, most elegant exhibition center of the modern world, Sir Joseph Paxton's iron and glass Crystal Palace, built in 1851, was even larger than the Washington Convention Center. Paxton provided 772,782 square feet of exhibition space, almost 12,000 more than Welton Becket et al.

Paxton's palace was instantly and universally admired for its simple beauty. It could show off that beauty because it took its distance from the crowd. It never occurred to the designer and his clients to cram the exhibition center into the London street pattern. The Crystal Palace was placed on a wooded, 26-acre site in Hyde Park.

(In 1854, it was moved to Syndenham and used as a museum. In 1936 it was damaged by fire. In 1941 it was demolished because it turned out to be a landmark for Luftwaffe pilots on their way to bomb London.)

Another attractive exposition building, the McCormick Palace in Chicago by architect C. F. Murphy, is similarly outside the city fabric. It is dramatic and yet it is inconspicuously located along the lake front.

With two Metro subway stations -- Metro Center and Gallery Palace -- within easy walking distance, New York Avenue and 11th Street may be more accessible than Hyde Park or the Chicago lake front, but are there really economic advantages in the Convention Center's downtown location?

The Center, we are told, will soon attract an annual 320,000 convention delegates not now coming to Washington.Their presence and the consequent development of hotels, restaurants and the like is expected to produce taxes of $42 million a year. The Center promises to create 4,000 sorely needed jobs for semi-skilled workers.

But would not all this happen just the same if the Center were elsewhere in the city where its size would be less disruptive?

In the few months since it was finally decided to build the Center, there has been a spurt of new building and planning downtown. Some of it is in the immediate vicnity of the Center site, but much is taking place in other parts of downtown. The new activity is not generated by the Center's specific location, let alone its design. It is generated by the fact that downtown Washington promises to host large conventions and trade shows.

It would be delightful, of course, if the Center, at its present location, would indeed make the dreary shopping streets between New York and Pennsylvania avenues more lively and attractive. But I don't think we can count on it.

As now designed, the Center is not a place where anyone would go except to conduct business. It is not a place where anyone would dwell when there are no conventions and exhibits -- which is the better part of the time. Chances are that here, as in most downtown convention centers in America, people never venture outside, except to go home or to escape to a more congenial environment.

The Center does nothing to make its environment more congenial. New York Avenues) east of the Greyhound Bus Terminal features a blank wall, hiding the loading docks. At 11th Street, opposite the former Annapolis Hotel, and toward a possible new Woodward & Lothrop department store annex, there are also blank walls.

Only on H Street with its main pedestrian entrance will the Center give us some shops -- seven, to be exact. That hardly promises to attract free-spending crowds. The 9th Street side is devoted to the taxi and bus driveway. Not much chance for urban ambience or elegance there.

In short, our clumsy center might as easily further depress as revitalize its immediate and dismal vicinity. It might drive the conventioneers to seek solace and spend money in Georgetown and the new mid-town and Westend districts.

To keep them downtown, something will have to be done for downtown. The recent renaissance on Pennsylvania Avenue is a promising beginning. What is needed in the old downtown core is the sort of drive, creativity, enthusiasm and leadership shown in the last few years by the planners, merchants and developers of downtown Baltimore and Boston.