The details and design formulae of steel moment resistant frame connections reinforced by haunch enlarged beam flanges welded to the column diaphragm were put forward based on the suggestion of Recommendation for Design of Connections in Steel Structures of Japan.Then,4 one-half scale T-shape specimens were designed based on the Chinese codes with enlarged flanges of H-shape beam welded to the diaphragm of diaphragm-through type columns.The specimens considered the influences of the width-to-thickness ratio...