矩形断面RC梁の曲げひび割れ幅算定式の適用性評価

摘要

Synopsis Bending loading tests on RC beams of different effective heights were conducted and the results were compared with those yielded by typical bending crack width calculation formulas (Japan Society of Civil Engineers Standard Specification for Concrete Structures, ACI 318-11, BS EN 1992-1-1：2004). For each formula, there were cases of sectional geometries and rebar placements for which the maximum bending crack width value was underestimated. Moreover, in addition to the covering and the on-center spacing of rebars as factors controlling the bending crack width, consideration of the influence of the effective height was demonstrated to be of importance in order to create a highly accurate bending crack width calculation formula.%有効高さが異なる鉄筋コンクリートRC梁の曲げ載荷試験を行い，代表的な曲げひび割れ幅の算定式(土木学会コンクリート標準示方書，ACI 318-11,BS EN 1992-1-1：2004)との比較を行った。いずれの算定式も，曲げひぴ割れ幅の最大値を過小に評価する断面形状寸法と鉄筋の配置の例があった。また，曲げひび割れ幅の支配要因として，かぶりや鉄筋の中心間隔以外に，有効高さの影響を考慮することが精度の高い算定式を構築する上で重要であることを提示する。