English to Spanish Tech/Engineering Other Racks - Warehouses

The document refers to a system of racks for huge warehouses. I am completely in the dark with regards to all these “back-to-back” terms, and in fact, almost with the whole paragraph!

Here is some context:

"System Type: The XXX system is a bolted, structural steel storage rack system.

Rack Connection Design: Rack connections are not intended to be made to wall panels or to building columns or the roof structure. Back to back rows are intended to be secured with a minimum of two back to back ties vertically per back to back upright frame. Single rows, where necessary, are intended to be tied overhead cross aisle to adjacent back to back rows. The system is intended to be secured to a concrete floor with a minimum of one anchor bolt per Base Plate."

Thank you in advance for all your suggestions!