In this way, in order to reduce the overall static load (dead weight) of steel-concrete structures, people have taken a series of measures to reduce the weight of steel-concrete structures, such as using lightweight concrete and using components with more reasonable cross sections, such as box structures, I-beams and U-beams.

The literal meaning is this:

In this case, these measures, such as: (using lightweight structural concrete, reducing the weight of ordinary rigid-concrete structures by designing components with more reasonable sections in the mechanical sense, such as box structures, I-beams, U-beams, etc.), have been used for a long time, with the aim of reducing the overall weight of RC (reinforced concrete) structures.