回顾了套管钢筋混凝土柱的发展过程。在套管钢筋混凝土柱中，套管用作柱中的横向增强，主要起约束和抗剪作用。Thomii和作者等人在1985年首次提出套管柱的概念，并验证了套管柱能够有效防止柱的剪切破坏并显著提高柱的延性。随后，这一概念被推广到利用焊接钢管和纤维增强塑料外包壳加固既存钢筋混凝土柱。本文还展望了使用纤维增强塑料套管进行新建柱设计的研究。

This paper introduces an innovative concrete filled steel tubular (CFT) column structure for improved seismic design of steel and concrete composite structures. Based on fundamental mechanics, the design concept is aimed at controlling the local buckling of the steel tube and confining the concrete in the potential plastic hinge zones of a CFT column. To achieve this, several efficient details of transverse confinement have been examined through experimental testing. The new type of CFT column, named as CCFT, is expected to overcome many disadvantages of the conventional CFT column and to provide the ideal choice for structural design of tall buildings in seismic regions. Experimental tests validated the concept of the CCFT.

This paper introduces an improved steel jacketing method to retrofit reinforced concrete columns with a square or rectangular section for enhanced strength and improved ductility. To retrofit an existing column, relatively thin steel plates were welded to form a rectilinear jacket for shear strength enhancement, and then additional confinement elements stiffeners! with various types of desired configurations were welded to the potential plastic hinge regions to ensure a ductile behavior. A rational retrofit design procedure was suggested and evaluated through an experimental program. Five 1/3 scale model columns were tested under constant axial load of 0.3Ag f c8 and cyclic lateral force in a double-curvature condition. Test results validated the efficiency of the partially stiffened rectilinear steel jacketing, which not only prevented brittle shear failure but also greatly improved the ductility of the column with achieving an ultimate drift ratio of more than 8%. Besides the structural merits, the partially stiffened rectilinear steel jackets also have appealing architectural features.

This paper describes axial compression test results of 27 concrete cylinders confined by carbon fiber reinforced polymer composite jackets. The experimental parameters include plain concrete compressive strength and the thickness of the composite jacket. It is found that the carbon fiber composite jacketing can significantly increase the compressive strength and ductility of concrete. The test results indicate that concrete strength and confinement modulus, defined as the ratio of transverse confinement stress and transverse strain, are the most influential factors affecting the stress-strain behavior of confined concrete. The failure of the confined concrete was dominated by the rupture of the jacket at an average strain much smaller than the ultimate strain obtained from tension tests of flat coupons. In order to describe the main mechanical features of the confined concrete, a simple bilinear stress-strain model is suggested based on the theory of elasticity and minimum number of empirical equations determined from the tests. The simple model is shown to compare well with test results from previous studies by other researchers.

This paper describees theoretical and experimental studies related to seismic assessment and retrofit of bridge columst footings. One "as built" model columm footing and three retrofit model colunzn footings have been tested under sinmulated seiatnic actions. Test results of the "'as built" footing indicated that columu/footing joint shear failure is a potential danger to existitng bridge, structures. Test results also indicated that if there is no dependable tensile capacity in the pile/footing connectiosz, a rocking behaveior may dominare pier resporzse, minimizing damage to footing and column. Model column footitzgs retrofit using current retrofit standards depeloped relatively stable hysteretic responses up to moderate ductility levels. However. experinzental obserations and theoretical analyses based on a strut-and-tie model and yield-line theory indicated that with current footing retrofit design, which lacks the consideration for joint shear design, the reiinforced concrete overlay may not develop a fully effective postcracking tnechanism. Improved retrofit details including long dowels to insure developnent of an effective joint shear-resistitlg nlechatlism are proposed and verified hy experimental results.