ACI Committee 335, Hybrid and Composite Structures, is pleased to sponsor an ongoing series of articles with the general theme “Hybrid Construction—History and State-of-the-Art.” This series began with “Making Composite Members Composite,” and has included “Hybrid Bridges in Texas,” and “Seismic Retrofit of Bridge Foundations.” This month, we continue the series with two articles: “Composite Moment Frames,” and “Hybrid Coupled Wall Systems.” Both articles provide historical perspectives as well as illustrate the advantages of using hybrid systems in the design of buildings to resist seismic effects

Studies have demonstrated that composite systems have the strength, stiffness, and ductility to safely resist large earthquakes. This recent full-scale frame test further validates the reliability of the composite frames using innovative precast construction details

Several studies have shown that improper first-day curing of test cylinders during hot weather can cause laboratory- measured compressive strengths to be up to 15% lower than those for properly cured cylnders