Papers by Keyword: Steel Frame

Abstract: Steel structures are commonly used in seismic regions of the world because of its strength and ductility. However, these structures are still prone to damage during an earthquake. With this risk of seismic damage, the strengthening of steel structures is a major concern in order to resist the dynamic loads resulted from earthquakes. This report investigates the potential for the use of Carbon Fibre Reinforced Polymer (CFRP) to strengthen the rigid steel frame under a real earthquake load. This research will be undertaken using Strand7, a finite element (FE) analysis software. To validate the accuracy of this research, the finite analysis results have been compared to the available experimental study by the Authors. First, both FE models of a five-story bare steel frame and CFRP strengthened steel frame has been developed. Then the predicted numerical results of bare steel frame and CFRP strengthened steel frame under earthquake excitation are compared. The results indicated an increase in the seismic performance of the steel structure due to the strengthened with CFRP. The CFRP strengthened steel frame showed 15% less tip deflection compared to bare steel frame. Further analysis on the strengthening capabilities of higher thickness CFRP was performed to assess the effect of the thickness of CFRP and the higher thickness CFRP showed better seismic performance compare to normal thickness CFRP by reducing 34.38% of tip deflection.

Abstract: The constraint of frame column has a significant effect on its dynamic response under blast loading. To study the influence factors of column end constraint, the effect of adjacent members and distributed mass of floors is studied using numerical analysis. The results show that the members that are directly connected to the column end are the main contributors to its end constraint. And these adjacent members may be simplified as being fixed at the far ends. It has also been found that the displacement at the column end decreases with the increase of the column end floors mass. The results in this paper is useful for the further derivation of column end constraint model.

Abstract: This paper presents some preliminary results from the numerical investigations of different interventions for the seismic upgrading of a masonry bell tower. Masonry bell towers belong to the cultural and historical heritage, are very widespread in Italy and their conservation has been given special attention in recent years. Their high vulnerability is related to the combination of mechanical material properties, geometrical irregularities, presence of inclination, foundation settlements and seismicity of the area. The present tower is located in Emilia Romagna Region, Northern Italy, recently stricken by a strong seismic sequence in May 2012. Analyses results show that the retrofitting of masonry bell towers is highly recommended in order to mitigate their present seismic risk. Four different upgrading techniques, consisting of grouted mortar, FRP sheets, internal steel frame and prestressing vertical rods, are investigated and compared in terms of structural performance improvement. The grouted mortar and internal steel frame techniques are found to be reasonable solutions when compared to the other proposals for the specific seismic intensity level. Furthermore, the other techniques have a relatively high level of invasiveness which is recommended to be avoid where possible. Experience has shown that the most effective interventions are those that not only protect the structure, but also preserve the built heritage.

Abstract: Resistance to progressive collapse under extreme loading is a measure of the structural robustness, and relies primarily on resistance of key elements, continuity between elements and ductility of elements and their connections. In case some hazards occur simultaneously or consecutively in a very short period of time, e.g. fire after explosion or impact, the capacity of the members and connections can be exceeded and this can initiate the progressive collapse of the structure. The paper presents the results of a research program that focused on the ultimate capacity of connection macro-components under large deformation demands and different loading rates. The specimens were extracted from extended end plate bolted beam-to-column connections with different strength and stiffness ratios to the beams.

Abstract: Buckling-Restrained Brace (BRB) in China, Taiwan, and Japan, as a kind of hysteretic damper has been installed into steel frame structure; In the United States, however, it has been installed into the hinge-connected steel framework, as the main seismic element in order to add lateral stiffness and strength.This paper according to the design codes of frame structure in China, Japan and the United States,establishes the research model based 0n the typical steel frame form of China, Japan, and the US.The main research parameters of the model are horizontal force sharing ratio of BRB (β) and frame strength of BRB (CB)。Through the steel consumption,the relationship of story drift and story shear, the formation of plastic hinge of the design model,it compares the steel frame seismic design method of China, Japan and the United States.The steel consumption of frame is related to the strength of the frame, but has nothing to do with the frame structure form;The plastic hinge of each model focused mainly on the BRB,reflecting the overall mechanism; As to seismic design requirements, the Japanese codes are stricter, codes of China and the United States is relatively close.

Abstract: To research the mechanical regularity of steel frame in tunnel, Steel frame and Sprayed concrete Combination Model is applied and the large-section loess tunnel of highway is taken as an example. The hoop stress of flange and the radial stress of web were analyzed, the research results show that:The most areas of hoop stress of flange is in press, the compress value which most areas of flank edge is larger than the outer flank flange in the same area of steel frame. The hoop and radial stress of web is in press. The hoop stress value which most areas of flank edge are larger than the radial stress in the same area of steel frame.

Abstract: Buckling-restrained braces (BRBs) and self-centering buckling-restrained braces (SC-BRBs) have been verified as novel energy dissipation bracing systems. This paper conducted a comparative investigation on the seismic-resisting performance of a Benchmark steel frame with these two types of bracing systems using the finite element analysis software OpenSEES. The analysis demonstrated that, in the equal-strength design principle, the SC-BRB frame results in weaker energy dissipation, bigger story drifts, and more evenly distributed story drifts along the building height compared to BRB frame. The residual deformations of SC-BRB frame under strong earthquakes are significantly smaller than the pure frame as well as BRB frame, but the maximum axial bracing force and floor accelerations are increased significantly for SC-BRB frame.

Abstract: To study the effect of damping on seismic performance of steel frame, using the pseudo dynamic test by inputting damping and no damping to analyze the seismic performance of semi-rigid steel frame. Analysis was focused on the effect of damping on the panel zone strain, story drift and interlayer force.The conclusion was that under the more severe earthquake, the structural damping had effects on the seismic performance of semi-rigid steel frame.

Abstract: This paper analyses the frame without mild steel dampers and the frame installed the new T-type , box –type and S-type mild steel dampers by FEM ABAQUS. The results shows the frame installed the new mild steel dampers have smaller yield displacement and the fuller hysteresis curve at low cyclic load, but the initial stiffness, yield strength , stiffness after yielding are greater. Research shows that the new type mild steel dampers have good energy performance, and have the better effect to seismic framework.

Abstract: The steel frame with wedge devices is a kind of shock structure based on the node energy consumption. The seismic performances of steel frame with wedge and ordinary steel frame model under low cycle reciprocating load simulation analysis and time history analysis under earthquake loads are analyzed by using finite element software, compared the respective energy dissipation performance and seismic performance, the results show that the wedge spring damping device can effectively control story drifts of structure, reduce the seismic response of structure, and well consume the seismic energy, so the structure of the new column bases with wedge spring devices show better seismic performance.