Design methods and construction techniques for the outer-jacketing structure reconstruction (extension) project of the Suifenhe Qingyun Market

In connection with the reconstruction (extension) project of the Suifenhe Qingyun Market, a design approach is proposed, in which similar links are employed to connect the newly-added frame and the original structure only at the roof of the original building, and the new structure and the original structure are connected by links at each floor after settlement of the new structure is complete. Similar connections between the original structure and the outer-jacketing frame columns are formed during construction by using concrete blocks placed between the roof of the original building and the outer-jacketing frame columns and by prestressing the reinforcing tendons between the two outer columns. After the new structure is constructed, steel bars embedded in the two outer columns at the height of the roof of the original building are welded together, and concrete of a certain depth is cast. In this way, the permanent firm connection between the roof of the original structure and the new structure is formed. The post-installed steel bars in the original frame joints are welded with embedded steel bars in the outer columns to work as the connection at each floor. In order to ensure that the original building works as usual during the construction, the design and construction methods of self-supporting concrete floor during construction are presented, the main idea of which is that the steel truss suspended by formwork can bear the construction load of encased steel-truss-concrete composite beam, that the steel box suspended by formwork can support the construction load of encased steel-box-concrete composite beam, and that the channel welded perpendicular to the encased steel box can carry the floor load.