A floor plate assembly system for assembling a plurality of floor plates of a building around a vertical support core of the building for a top-down construction process in which the plurality of floor plates are assembled, raised, and attached to the vertical support core sequentially in a descending order, the floor plate assembly system comprising: an assembly pad formed from a hardenable material, the assembly pad positioned around a periphery of the vertical support core of the building, wherein the assembly pad includes a top surface disposed at a ground level elevation of the building, and covers a footprint of the building; the floor plate assembly system characterized in that it further comprises: a plurality of tie-downs attached to the assembly pad and configured to provide a restraining force against upward vertical movement relative to the assembly pad; a plurality of jack pedestals positioned on the assembly pad and configured to support each of the floor plates, and raise and lower each of the floor plates relative to the assembly pad; and a system controller in communication with each of the plurality of jack pedestals; wherein the system controller is operable to precisely control extension and contraction of each respective one of the plurality of jack pedestals, such that a camber is configured to be formed into one or more frame members of a respective one of the plurality of floor plates in situ by restraining a respective one of the frame members against vertical movement relative to the assembly pad at two locations along a length of the respective frame member with the plurality of tie-downs, and controlling a respective one of the plurality of jack pedestals to extend a distance to bend the respective frame member and introduce a controlled amount of camber into the respective frame member in situ relative to the respective one of the plurality of floor plates. an assembly pad formed from a hardenable material, the assembly pad positioned around a periphery of the vertical support core of the building, wherein the assembly pad includes a top surface disposed at a ground level elevation of the building, and covers a footprint of the building; the floor plate assembly system characterized in that it further comprises: a plurality of tie-downs attached to the assembly pad and configured to provide a restraining force against upward vertical movement relative to the assembly pad; a plurality of jack pedestals positioned on the assembly pad and configured to support each of the floor plates, and raise and lower each of the floor plates relative to the assembly pad; and a system controller in communication with each of the plurality of jack pedestals; wherein the system controller is operable to precisely control extension and contraction of each respective one of the plurality of jack pedestals, such that a camber is configured to be formed into one or more frame members of a respective one of the plurality of floor plates in situ by restraining a respective one of the frame members against vertical movement relative to the assembly pad at two locations along a length of the respective frame member with the plurality of tie-downs, and controlling a respective one of the plurality of jack pedestals to extend a distance to bend the respective frame member and introduce a controlled amount of camber into the respective frame member in situ relative to the respective one of the plurality of floor plates. a plurality of tie-downs attached to the assembly pad and configured to provide a restraining force against upward vertical movement relative to the assembly pad; a plurality of jack pedestals positioned on the assembly pad and configured to support each of the floor plates, and raise and lower each of the floor plates relative to the assembly pad; and a system controller in communication with each of the plurality of jack pedestals; wherein the system controller is operable to precisely control extension and contraction of each respective one of the plurality of jack pedestals, such that a camber is configured to be formed into one or more frame members of a respective one of the plurality of floor plates in situ by restraining a respective one of the frame members against vertical movement relative to the assembly pad at two locations along a length of the respective frame member with the plurality of tie-downs, and controlling a respective one of the plurality of jack pedestals to extend a distance to bend the respective frame member and introduce a controlled amount of camber into the respective frame member in situ relative to the respective one of the plurality of floor plates. a system controller in communication with each of the plurality of jack pedestals; wherein the system controller is operable to precisely control extension and contraction of each respective one of the plurality of jack pedestals, such that a camber is configured to be formed into one or more frame members of a respective one of the plurality of floor plates in situ by restraining a respective one of the frame members against vertical movement relative to the assembly pad at two locations along a length of the respective frame member with the plurality of tie-downs, and controlling a respective one of the plurality of jack pedestals to extend a distance to bend the respective frame member and introduce a controlled amount of camber into the respective frame member in situ relative to the respective one of the plurality of floor plates.