Beginning with the internal frames of steel that made skyscrapers possible in the 1880s, Chicago has long been a center of innovative structural design. But the developers cranking out formulaic apartment high-rises in the current building boom have shown scant interest in breaking out of the box. As a result, many of the city’s top architects have been exporting their best ideas to fast-growing parts of the world, like China, that are more receptive to new ideas. Now, ironically, Chinese money — in the form of the Wanda Group’s investment in the Vista Tower— is bringing leading-edge concepts back to Chicago.