Strengthening of concrete members using steel plates is a well known and an extensively applied technique. Fibre reinforced polymer (FRP) composites have been established as an alternative method for rehabilitation and strengthening of concrete structures. In this project, reinforced concrete (RC) beams had been externally strengthened with glass fibre reinforced polymer (GFRP) sheets. In order to investigate the load capacity and member failure by altering the number of bonded layers (two or four), a series of static tests was carried out. Results show that, by the use of U-jackets, the deflection is reduced and the load capacity of the member is increased up to four times compared with the conventional RC beams. Two failure modes were observed; failures of the GFRP close to the mid-span area (when 2-layers GFRP had been used) and a shear failure between the GFRP sheet and the concrete surface at the end of the beams (when 4-layers were used).

A new type of composite column, i. e. structural steel and concrete-filled steel tube (SCFT), was proposed. In the composite column, structural steel was embedded in concrete-filled steel tube (CFT). The mechanics of the composite columns were analyzed, including stresses, strains of concrete, steel tube and structural steel, and buckling of steel tube. The results show that the column has higher bearing capacity and excellent ductility. The ultimate bearing capacity and ductility of the column decrease with the increase of slenderness ratio. The strength of concrete depends on extremely the thickness of steel tube and sizes of structural steel. The distribution of strength of concrete varies with position in cross section even at the same load. Based on above analysis, formulas for predicting the strength of concrete and ultimate bearing capacity of the composite columns are suggested.

The flocculation procea can be described by flocculation kinetics．A silica pa rticle SuY,pensi(in was coag ulated with inorganic coagulants，and the flocculation kinetics was studled through easuring and anaIyzing the vari-ation of particle number during the floceuiation process The resuIts show that the flocculation kinetics；Ire lnfIu enced by the flocculation time. coagulant dosages and coagulant kinds，erc The flocculation process follows the first-order reaction in the beginning phase for about 10min; within the later time the flocculation process does NOT foBow the first-order reaction any nlore．With increasing coagulant dosage the floeculation rate inerease，and with the larger dosages the flocculation process goes on rapidly，deviating from the first-order reaction．The effective co-agulants Can improve the flocculation rate．

Fibre-reinforced plastic (FRP) materials have been thought as new innovative materials for concrete rehabilitation and retrofit, the bonding of FRP plate to reinforced concrete (RC) structure has been a popular method for strengthening deficient RC structure. This paper presents a finite element investigation into interfacial stresses in an FRP plate partially bonded concrete beam. The finite element results show that both normal stress and shear stress at the a middle to adhesive section are influenced by the material and geometry parameters and the length of debonding FRP plate of the beam

More and more isolators are widely used all over the world. For a structure with isolator between base and super-structure, it is suitable to take only the first-mode in consideration for the super-structure, the structure become a 2-DOF system, and its damping and stiffness matrices are non-symmetrical. The equation of motion cannot be decoupled by the mode-superposition method. A complex-mode method is proposed and analytic expressions are obtained under earthquake excitation in the paper. Base on above analytic expressions suggested by authors, an isolator index β(the ratio of the standard deviation of the displacements at the top of super-structure), an optimal design process and some useful data are achieved. All of these are meaningful in practice projects.