Anti-collapse performance of concrete-filled steel tubular composite frame with RC shear walls under middle column removal

Seismic behaviour of concrete-filled steel tubular frame to RC shear wall high-rise mixed structures

Cyclic testing of steel beam blind bolted to CFST column composite frames with SBTD concrete slabs

Anti-collapse performance of concrete-filled steel tubular composite frame with assembled tensile steel brace under middle column removal

As per seismic studies, vertical irregular RC buildings show major weakness in earthquake areas. Regarding structural behaviour, geometry breaks increase side forces during ground shaking. Moreover, this study actually examines how G+10 RC buildings with setback irregularities perform during earthquakes, focusing on RC and GFRP shear walls. The study definitely determines which type of shear wall works better for these irregular building shapes. Moreover, a total of 4 models with different setback configurations were developed in ETABS software. Further, Response Spectrum Analysis was used to find the peak responses when the structure itself experiences seismic forces. The critical setback configuration was identified, and the optimum shear wall location was taken at corners only from the earlier study. As per the critical cases, a comparative study was conducted regarding conventional RC shear wall and GFRP reinforced shear wall. Both types were compared to find the differences. Results show that the RC shear walls actually made buildings much stiffer and reduced displacement by up to 42.324% and drift by up to 47.708%. GFRP shear walls definitely reduced displacement by up to 39.569% and drift by up to 44.798%, but RC walls actually handled more base force because they were stiffer. The findings highlight the trade-offs between RC and GFRP shear walls and provide practical insights into selecting an appropriate shear wall in irregular high-rise buildings.

Anti-collapse mechanism and reinforcement methods of composite frame with CFST columns and infill walls

The effective length of concrete filled steel tubular (CFST) frame columns is a key parameter to determine its ultimate strength for engineering design. There was no special design code, so engineers usually got the values according with specification for steel structure. This may cause error in some degree. Based on liner and non-linear buckling analysis respectively, the overall stability of a typical planar composite frame with CFST columns and steel beams was performed in this paper. By comparing the results of finite element method with current approach, some primary conclusions were given to refer for engineering practice on the composite frames.

Purpose This paper aims to obtain fire resistance of semi-rigid joints for concrete-filled steel tubular (CFST) composite frames and temperature filed distribution of composite joints in fire. Design/methodology/approach The temperature filed model of semi-rigid joints to CFST columns with slabs was made by using ABAQUS finite element (FE) software, in considering temperature heating-up stage of fire modelling. The effects of composite slab, fire type and construction location were discussed, and the model was verified by the test results. The temperature distribution of composite joint under three-side or four-side fire condition was studied by the sequentially coupled thermal analysis method. The temperature versus time curves and temperature distribution of various construction and location were analyzed. Findings The paper provides FE analysis and numerical simulation on temperature field of semi-rigid joints for CFST composite frames in fire. The effects of composite slab, fire type and construction location were discussed, and the model was verified by the test results. It suggests that the temperature distribution of composite joint in three- or four-side fire condition showed a different development trend. Research limitations/implications Because of the chosen FE analysis approach, the research results may lack generalizability. Therefore, researchers are encouraged to test the proposed propositions further. Practical implications The research results will become the scientific foundation of mechanical behavior and design method of semi-rigid CFST composite frames in fire. Originality/value This paper fulfils an identified need to study the temperature field distribution of the semi-rigid joints to CFST columns and investigate the mechanical behavior of the semi-rigid CFST joints in fire.

Progressive collapse resistance of composite frame with concrete-filled steel tubular column under a penultimate column removal scenario

This paper presents a nonlinear finite element (FE) analysis on the mechanic behavior of concrete filled steel tubular (CFST) composite frames. The main purpose of the FE analysis was to investigate the seismic behavior of composite frames. Three kinds of nonlinearity, namely material nonlinearity, contact nonlinearity and geometry nonlinearity, were taken into account in the FE model using MSC.Marc. The element type, connection between element, material constitutive law and boundary condition was described in detail. The elasto-plastic behavior, as well as fracture and post-fracture behavior, of the FE analysis models fitted well with those of the test specimens. The beam and panel zone deformation of the analysis models is also in good agreement with that of the test specimen. It is concluded that FE model of CFST composite frame is reliable and could be regarded as a helpful tool to expand the information on seismic behavior of CFST composite frame.

The progressive collapse of a concrete‐filled steel tubular (CFST) frame structure is studied subjected to impact loading of vehicle by the finite‐element software ABAQUS, in the direct simulation method (DS) and alternate path method (AP), respectively. Firstly, a total of 14 reference specimens including 8 hollow steel tubes and 6 CFST specimens were numerically simulated under transverse impact loading for verification of finite‐element models, which were compared with the existing test results, confirming the overall similarity between them. Secondly, a finite‐element analysis (FEA) model is established to predict the impact behaviour of a five‐storey and three‐span composite frame which was composed of CFST columns and steel beams under impact vehicle loading. The failure mode, internal force‐time curve, displacement‐time curve, and mechanical performance of the CFST frame were obtained through analyzing. Finally, it is concluded that the result by the DS method is closer to the actual condition and the collapse process of the structure under impact load can be relatively accurately described; however, the AP method is not.

Pseudo-dynamic tests of assembly blind bolted composite frames to CFST columns

As the most basic structure, the concrete‐filled steel tubular (CFST) frame has been widely used in various structures and systems. Compared with conventional reinforced concrete structures and steel structures, CFST structures in strong earthquake showcase more complicated strength and deformation behavior because there are many factors underlying the failure mode. Furthermore, according to the specifications at home and abroad, the corresponding design method to achieve reasonable failure modes for CFST structures has not been clarified. Based on a destructive test on steel beam‐CFST plane frames under constant axial load and lateral load, the fiber mode method and solid element model method are adopted to simulate the failure process of the test frames. Based on finite element model simulations and tests, the fiber model method is proposed to carry out the pushover analysis on the CFST frame structures. The factors behind the reasonable failure mode of steel beam‐concrete‐filled circular steel tubular (CFCST) frame structures are analyzed. Furthermore, the law and influencing factors behind the ratio of flexural capacity of column to beam, the ratio of line stiffness of beam to column, and the ratio of axial compression on the deformation, bearing capacity, and failure modes of the structure are discussed. Some suggestions on the design of reasonable failure mode of steel beam‐concrete‐filled circular steel tubular (CFCST) frame structures are proposed.

The effective length of concrete filled steel tubular (CFST) frame columns is a key parameter to determine its ultimate strength for engineering design. There was no special design code, so engineers usually got the values according with specification for steel structure. This may cause error in some degree. Based on liner and non-linear buckling analysis respectively, the overall stability of a typical planar composite frame with CFST columns and steel beams was performed in this paper. By comparing the results of finite element method with current approach, some primary conclusions were given to refer for engineering practice on the composite frames.

In order to study the parameters influence on seismic behavior of concrete filled steel tubular (CFST) frame with bucking-restrained brace (BRB), the finite element analysis for CFST frame with BRB is studied in this paper, which is performed under low cyclic loading using the software of ABAQUS. Failure model and skeleton curve are comparative analyzed with the related experiment components, verifying that the finite element simulation of the CFST frame with BRB is effective. By changing the axial compression ratio of the column(n) and the steel ratio(α) of the column section respectively, the effect of the structural parameters on the seismic behavior of the CFST frames with BRB had been studied. The results shows that: with the increase of steel ratio of the column section, the lateral ultimate strength and the initial stiffness of the frame get higher, the lateral load(P) versus lateral displacement (Δ) hysteresis curves of the frame get plumper, and the energy dissipation of BRB remain basically unchanged; With the increase of axial compression ratio of the column, the lateral ultimate strength and the hysteretic behavior of the frame become low, whilst the energy dissipated by the BRB get higher.

In order to further improve the seismic performance of RC shear walls, a new composite shear wall with concrete filled steel tube (CFT) columns and concealed steel trusses is proposed. This new shear wall is a double composite shear wall; the first composite being the use of three different force systems, CFT, steel truss and shear wall, and the second the use of two different materials, steel and concrete. Three 1/5 scaled experimental specimens: a traditional RC shear wall, a shear wall with CFT columns, and a shear wall with CFT columns and concealed steel trusses, were tested under cyclic loading and the seismic performance indices of the shear walls were comparatively analyzed. Based on the data from these experiments, a thorough elastic-plastic finite element analysis and parametric analysis of the new shear walls were carried out using ABAQUS software. The finite element results of deformation, stress distribution, and the evolution of cracks in each phase were compared with the experimental results and showed good agreement. A mechanical model was also established for calculating the load-carrying capacity of the new composite shear walls. The results show that this new type of shear wall has improved seismic performance over the other two types of shear walls tested.