单向体外预应力加固RC双向板的试验研究

Experimental Study on RC Two-way Slabs Strengthened by One-way External Prestressing

对RC双向板的加固采用粘贴补强技术存在诸多施工难点,如混凝土板底的大面积打磨处理、粘胶层涂抹时的厚度控制、大面积钢板的安装就位等等。体外预应力加固技术则不存在上述问题,它不仅施工方便,而且可以主动消除新加部分的应力滞后。通过5块RC简支双向板的单向体外预应力加固试验,研究了预应力钢筋的张拉控制力及其布筋形式对双向板受力性能的影响。试验结果表明,体外预应力可有效地改善双向板的受力性能,提高双向板的极限承载能力,在双向板的跨中区段"集中布置"体外预应力钢筋加固效果最佳。

At present, applications and studies on strengthened RC two-way slabs are mostly based on external bonding method. However, this kind of method has many problems in construction, such as a great deal roughening work, the thickness control of adhesive layer and inconvenience of construction for large plates etc., all such difficulties obstruct its application in practice. While, external prestressing method has not these problems, and it is not only ease of construction, but also can avoid stress lag. Therefore, based on the tests of five pieces of simply supported two-way slabs strengthened by one-way external prestressing, the effects of different initial stresses and layouts of tendons on the behaviours of slabs were studied. Experimental results showed that external prestressing improved the behaviours of two-way slabs greatly, increased the ultimate bearing capacity of slabs, and the layout with dense tendons in the midst of slab was more efficient.