ACI 550.4-18 PDF Download

ACI 550.4-18 is a standard that provides guidelines for the qualification of precast concrete diaphragm connections and reinforcement at joints for earthquake loading. The standard specifies testing and evaluation requirements for mechanical connections and reinforcement at joints used in precast concrete diaphragms, which are responsible for transferring forces between the diaphragm members and vertical elements of the seismic-force-resisting system.

It is important to consider not only the strength, but also the stiffness and deformation capacities of these connections and reinforcement at joints in order to accurately predict the response of precast concrete diaphragms under earthquake loading. The seismic forces specified in ASCE/SEI 7 for the design of precast concrete diaphragms are linked to the shear overstrength provided by these connections and reinforcement at joints. The ACI 550.4 standard provides experimental procedures to assess the stiffness, strength, and deformation capacity of these connections, specifically for diaphragm flange-to-flange connections in double-tee beams.

It is worth noting that ACI 550.4 does not cover experimental procedures for assessing the same information for connections in hollow-core members used in the untopped condition.