Experimental Study On RC Two-way Slabs Strengthened In One-way Method

Study on strengthening-techniques in Concrete structure is popular in civil engineering. Compared with developed countries, the level of our Strengthening-techniques isn't in advance, many problems need to be solved. For example, to be the most ordinarily structure member, the strengthening-techniques in RC two-way slab has been the hotspot problem.Of all the kinds of strengthening-techniques, strengthening reinforced Concrete structure using Fiber Reinforced Polymer(FRP) or steel plates has become widely accepted, its ultimate capacity and deformation stiffness are widely increased, its cracking-behavior is also improved. Compared with bonding FRP or steel plates, the external prestressing method has many advantages over the tradition ones, such as controlling stress actively and eliminating stress lag. These days, some studies on RC two-way slabs strengthen with bonding FRP or steel strips have been undertaken, but less work has been done in achieve its strengthening-aim by changing two-way slabs'isotropy behaviour through bonding one-way steel strips, at the same time, less work has been pursued in strengthening RC two-way slabs by using the external prestressing method. The following paper deals with this subject through model test, theory analysis and numerical simulation.The main content and achievement of this paper are briefly summarized as follows:1. The internal force and deformation of stiffness-changing two-way slabRC two-way slab is changed to been stiffness-changing slabs by bonding one-way steel plates, the elastic theory has been used in analysis the two-way slabs strengthen with bonding one-way steel strips. The research revealed that torsion reduced the bending deformation of slab-beam, the bending moment and side torsion of slab-beam are made up of the normal and shearing stress in cross section of steel plate and concrete slab-beam, bonding one-way steel strips reduced the load ratio of the slab-beam in its landscape orientation , the one-way strengthening method is in effect.2.The distribution of bond stressThe strip method is used to analysis the balance equation of one-way slab-beam in two-way slab by taking into account the influence of torsion, the bond normal stress and bond shearing stress are calculated, the difference of them in two-way slab and one-way slab is also compared.3.The internal force and deformation of two-way slabs under bending moment in slab sides and compressive stress in faceBy using of the Energy method, the calculating expressions of deformation of slabs under distributing or focus bending moment in slab sides and distributing or focus compressive stress in slab face are also presented. The difference theory is also used to analysis the distributing of internal force under all kinds of load conditions, VB is used to workout the calculating program, the validity of external prestressing in strengthen two-way slabs was proved by a example.7. Experiment study...