Special-shaped Columns Research Articles

Seismic Performance Analysis of the Special-Shaped Frame Column Structure on Multi-Dimensional Seismic

The article considers the two horizontal components of ground motion and torsional component, to do nonlinear time history analysis both on regular and irregular shaped column frame structure models. The results show that torsional component of ground motion haves some impact on torsion reaction of structures, stiffness of irregular shaped column frame structure is uneven, and angle of columns are greater than that of the regular structure; torsion haves some impact on the torque of structure, the torque increases of corner columns is maximum, so corner columns are weak links in shaped column structure, considered fully during the seismic design.

Stress Transferring Mechanism and the Bearing Capacity of Joints between Concrete-Filled Square Steel Tubular Special-Shaped Columns and Steel Beams

In recent years, a new type of frame consisting of steel beam and concrete-filled square steel tubular special-shaped column is increasingly widespread. Compared with the joint of ordinary reinforced concrete special shaped frame, the joint between concrete-filled square steel tubular special-shaped columns and steel beams has the advantage of better ductility, higher loading capacity, uncomplicated reinforcement disposing and convenience in construction. This paper indicates that the joint has strong energy dissipation capacity and high loading capacity, and the use of diaphragm is effective to enhance the structural performance of the joints. Stress transferring mechanism in the joints is discussed, and the calculating model of the shear strength of panel zone is established. This study is helpful for further study of the design and use of the joint between concrete-filled square steel tubular special-shaped columns and steel beams.

Experimental Study on Shear Capacity of Broad-Limb Special-Shaped Columns

The experimental study on shear capacity of 24 broad-limb special-shaped columns subjected to low cyclic loading were executed. The characteristic of hysteretic curve and skeleton curve were analyzed. The influences of the lateral bevel loads and the limb’s width-thickness ratio on the shear strength of the T-shaped and L-shaped broad-limb special-shaped columns were studied. The application of the shear formula in the current code for the broad-limb special-shaped columns was verified. It is shown that using the formula to calculate the shear strength of broad-limb special-shaped columns is safe from the results.

Compressive behavior of T-shaped concrete filled steel tubular columns

Special-shaped column structures improve residential architectural space, compared with traditional frame structures. However, in respect to applicable building height and seismic fortification intensity, traditional special-shaped reinforced concrete (RC) columns have strict limitations in seismic behavior, which hampers further generalization and application of special-shaped columns. Due to increase in constraint effect for concrete, special-shaped concrete-filled steel tube (CFST) columns are expected to behave advantages on the strength, ductility and seismic behavior over special-shaped RC columns. However, special attention should be paid to prevent the steel plates’ premature local buckling and the separation between steel tube and concrete at inner corners. The battlement-shaped bar stiffeners and tensile bar stiffeners, welded on tube surfaces, were first put forward in this paper. Experimental study of 9 stubs in three groups subjected to axial loads was conducted, and the specimens consist of 3 square stubs (including 1 non-stiffened and 2 stiffened CFST specimens) and 6 T-shaped stubs (including 1 RC specimen, 2 non-stiffened and 3 stiffened CFST specimens). Failure modes and static properties of the specimens were investigated. Experimental results reveal that: Due to the constraint effect provided by T-shaped tubes, the CFST specimens behave advantages on the RC specimen in the ascending stiffness, peak resistance and ductility (except for the battlement-shaped bar stiffened CFSTs). For square and T-shaped stiffened CFST specimens, the stiffeners improve their ductility, especially the tensile bar which gives the best performance in ductility and improves the peak resistance substantially. The stiffeners postpone the buckling of tubes, and even upgrade the classification of composite sections, without thickening the tubes.

Application of Special Shaped Column Composed of Concrete-Filled Steel Tubes

Special-shaped column composed of concrete-filled steel tubes (SCFT) structure, a new type structure, is adopted to a residential building. This paper represents the design and analysis of this structure. 3D model of the structure is built by finite element procedure software and vibration property, static and seismic performance of the building are also analyzed to check the safety of the structure. At last, the vertical stiffener joint of SCFT structure is proposed and calculated. The application of SCFT for residential building represents that the SCFT is suitable for real constructions.

Time History Analysis of the Non-Symmetrical Special-Shaped Column Structure on Multi-Dimensional Seismic

In this paper, the spatial analysis model of non-symmetrical special-shaped column is established in ANSYS, and then, the translational and rotational component of the seismic wave was input to the frame structural model, taking account of stiffness enhancement of the floor on the beam, and carried out the elastic-plastic time-history analysis. Simulations show that the trend of development of displacement basically the same way on two horizontal components and torsional acceleration component, and the displacement on two horizontal components and torsional acceleration component increases significantly compared with one horizontal component; because of the presence of the floor, the intensity of beam is enhanced, leading to some columns more strain than the beam, so the floor should be fully considered in the design of the beam.

Nonlinear Seismic Response of Special-Shaped Column Frame Structures

The spatial analysis model of special-shaped column frame structure is established in ANSYS. The nonlinear dynamic analysis is carried out for the structure by inputting ground motions in one direction. The seismic performance of the structure under rare seismic actions was examined and whether the structure achieved the predetermined seismic aims is evaluated. The results indicates that the structure which under the 8-degree zone designed according to the codes can achieve the predetermined seismic aims under the rarely occurred earthquake actions.

Bearing Capacity of Frame’s Column Strengthened with Addition Flange Wall

A large number of frames damaged due to the poor lateral stiffness in “5.12” earthquake. Additonal flange wall could effectively improve the lateral stiffness. This paper analyzed the behavior capability of special-shaped column of the practical engineering structures, meanwhile, obtained N-M curve, Mx-My curve and M-φ of biaxial eccentricity compression based on numerical integration method.The results show that,the failure mode of special section column after reinforcing and rectangular column under the biaxial eccentricity compression are conform,including fail in tension or compression and the limit failure. When the axial compression ratio is quite slightly,and section eccentric tension destruction, the thrust increases, the anti-bending ability increases.When section bearing destruction, along with axle strength enlargement, the anti-bending ability reduces.And the results reveal the axial compression ratio could influence the bearing capacity and ductility of frame’s column obviously.

Seismic behavior experimental study of frame joints with special-shaped column and dispersed steel bar beam

To overcome the problem that steel bars are put too close at a flame joint with special-shaped beam and column, mechanical performance of three groups of six RC flame joints with special-shaped (L, T and +) column and dispersed-steel bars-beam on the top floor under cyclic loads were studied. Experimental comparison was conducted between special-shaped (L, T and +) column and normal beams. The cracking load, yielding load, ultimate bearing capacity, failure patterns, and hysteretic properties at joint core area were investigated. The seismic behaviors of the joints with different proportions of dispersed-steel-bar beams were analyzed. The results of experimental analysis indicate that the mechanical and seismic behaviors of frame joints with T-shaped and +-shaped column are nearly not changed when suitable proportion steel bars are dispersed to flange plane. Stiffness degeneration of flame joint with L-shaped column is rather serious due to concrete damage stiffness. Theoretical result indicates that distributing area of the dispersed steel-bar beams in the flange plate should be strictly controlled to avoid anchor destroy.

EXPERIMENTAL STUDY ON MECHANICAL PROPERTY OF STEEL REINFORCED CONCRETE L-SHAPED SHORT COLUMNS

The horizontal press performance of column is deteriorated because of its special-shaped section. Moreover, because the antiseismic performance of column is worse, special-shaped column is only used in regions where seismic intensity is lower. So the main problem is to enhance the ductility and shear capacity. This test study on mechanical performance has been carried out through 14 SRCLSSC and 2 RCLSSC. The study focuses on the impacts of test axial load ratio (nt), hooped reinforcement ratio (ρ v ), shear span ratio (λ) and steel ratio (ρ ss ) on the shear strength and the antiseismic performance of SRCLSSC. It can be concluded that the shear strength of SRCLSSC is increasing with the increasing of n t and ρ ss , but the degree of increasing is small when n t is a certainty value, and that the shear strength of SRCLSSC is decreasing with increasing of λ; The shear resistance formula of L-shaped column is derived through tests, the calculated results are in correspondence with those of the tests. It also can be concluded that the hysteretic loops of the SRCLSSC are full and the hysteretic behaviors are improved; the displacement ductility is increasing with increasing of ρv and ρ ss , but decreasing with the increasing of n t ; the degree of variety in high axial load ratio is larger than that in low axial load ratio. If steel bars are added, the shear strength and displacement ductility of SRCLSSC are increased in a large degree.

Experimental Research on Seismic Behavior of Strengthened R.C. Frame with Special-Shaped Columns

In this paper, a damaged R.C. frame with special-shaped columns has been strengthened for earthquake resistance. The strengthening method combines wrapping steel outside and stick steel. The experimental research on seismic behavior of the strengthened frame was performed. Through the quasi-static test, the load-displacement hysteretic curves under horizontal low-cycle loading are given, and the failure modes of the strengthened frame structure are summarized. This paper gives the analysis of its bearing capacity, stiffness deterioration, energy dissipation capability and ductility property. After comparing the strengthened frame with that before damaged, we draw a conclusion that the method of seismic strengthening in this paper can effectually improve the carrying capacity of damaged R.C. frame with special-shaped columns, and make the strengthened frame have better ductility.

Seismic Behaviors of Concrete-Filled T-Shaped Steel Tube Columns

Concrete-filled special-shaped (L-shaped, T-shaped, and cross-shaped, and etc.) steel tube column is a type of member in which concrete is poured into special-shaped steel tube so that steel and concrete support loads together. It improves the seismic behaviors of reinforced concrete special-shaped columns due to the better confining effects provided by the steel tube. A test research on the seismic behaviors of one concrete-filled T-shaped steel tube column with pseudo static method is presented and the load-displacement curve and skeleton curve are provided. Series of steel bar stiffeners were welded onto the steel tube in order to postpone the buckling of steel tube and to enhance confining effects. A numerical analysis program was developed using a fiber-based method. The constitutive model of concrete employed the modified Mander model, and that of steel employed a bi-linear model considering the Bausinger effect. The numerical analysis program was verified by the test results and parametric analysis was carried out, in which the influences of the ratio of axial compression stress to strength, steel tube thickness and concrete strength were mainly discussed. The following conclusions are obtained: with the increase of the ratio of axial compression stress to strength, the bearing capacity of member increases and the energy dissipation capacity improve, while the ductility deteriorates. With the increase of steel tube thickness, the initial rigidity, bearing capacity, ductility and energy dissipation capacity improves simultaneously. With the increase of concrete strength, the bearing capacity increases, the energy dissipation capacity improves, while the ductility deteriorates.