矩形混凝土柱新的约束型式之研发(Ⅰ)一笔箍、格网箍筋及电焊方箍

RESEARCHES AND DEVELOPMENTS OF ALTERNATIVE CONFINEMENTS FOR RECTANGULAR CONCRETE COLUMNS(Ⅰ)

传统约束钢筋是由箍筋及系筋弯折绑扎而成 ,因此在组立钢筋笼的过程中 ,不仅耗工费时 ,且其约束效果常因绑扎不确实而有所折扣 ,因此便有“一笔箍”及“格网箍筋”等约束构想的成形。所谓“一笔箍”是指以一根钢筋弯折成形的约束钢筋 ;“格网箍筋”是以焊接组合钢筋形成格网状约束钢筋 ;“电焊方箍”是以电焊组合钢筋形成约束方箍。上述做法之优点在于可由机械作业取代传统约束之箍筋与系筋绑扎。本文共探讨 13组方柱试件之轴压试验结果 ,混凝土设计强度约为C80级 ,其中包含三组传统约束试件、五组“一笔箍”试件、四组“格网箍筋”试件以及一组组合电焊方箍试件 ,透过上述试验结果的分析与比对 ,说明上述各种型式箍筋之轴压行为 。

Conventionally, the confinements in rectangular concrete are composed of rectangular hoops and cross ties. It takes not only time to form the cages but also is hard in quality control. This paper will introduce three new rectangular confinements which were developed to raise the efficiency in forming the reinforcement cages. One of the alternatives is one-bar confinements which are formed by bending one steel bar. Wire mesh confinements and electric welded rectangular hoops are the other alternatives. Axial compression test results of 13 full-scale rectangular specimens are discussed in this paper. There are 3 traditional confined specimens, 5 one-bar confined specimens, 4 wire mesh confined specimens and one electric welded rectangular hoops specimen. High performance concrete (f c′=70 MPa) was adopted in these specimens. Test results show that the traditional confined specimens have better behaviors in both strength and ductility. Compression strengths of all specimens meet the general design requirements as well.