Capacity Of Steel Members Research Articles

Experimental investigations of residual stresses in thick high‐strength steel plates

AbstractResidual stresses strongly influence the load‐bearing capacity of steel members under compressive axial loads. Current developments in steel and steel‐concrete composite structures imply the use of high‐strength steel grades up to 960 MPa. For such steel plates, only limited results of residual stress investigations are known so far. The authors have applied two established measuring methodologies like the sectioning method and X‐ray diffraction to determine the residual stress state of 40 mm thick steel plates and different widths. The results show that the distribution and amount of longitudinal residual stresses are mainly determined by the oxyfuel‐cutting procedure used to manufacture the specimens. The distribution over the thickness could be determined by X‐ray diffraction. Compared to the results of examinations on lower‐grade steel plates an assumed correlation of residual stresses and steel grades could not be observed. Consequently, residual stresses have a reduced influence on the load‐bearing capacities of structures prone to buckling as the ratio of yield strength to residual stress states declines significantly.

Effect of cyclic flange local buckling on the capacity of steel members

Cyclic flange local buckling typically occurs when plastic hinges form in the beams and columns of special moment resisting frames subject to seismic excitation. While local buckling in beam plastic hinges has been investigated in the past for monotonic loading situations, the effect of cyclic flange local buckling on beam and column behaviours is not yet well understood. In order to address this shortcoming, nineteen half-scale T-section specimens are tested under cyclic axial loads in a configuration intended to replicate the cyclic demands imposed on flanges of beams and columns in their plastic hinge region. The main experimental variables are flange slenderness ratio, level of web restraint, and loading scheme (monotonic versus cyclic). Validated computational studies are performed to expand the parameter space. The test data and computational results show that T-section members that meet the current highly ductile limit can suffer excessive axial strength degradation under cyclic axial loading. The effect of slenderness ratios on column compression capacity due to strength degradation of flanges is evaluated and quantified.

Carbon-fibre strengthening of deficient hollow steel sections under combined loading

Strengthening of steel structures using carbon-fibre-reinforced polymer (CFRP) is a useful technique that has been considered by many researchers in recent years. However, most previous research studies have concerned the behaviour of structural steel members without deficiencies such as cracks and holes. The work described in this paper explored the effect of CFRP strengthening on the structural behaviour of square hollow section steel members having an initial deficiency under combined axial and lateral load. To study the effects of the strengthening, 17 specimens were tested under four loading scenarios, with 12 specimens strengthened using CFRP sheets. The deficiency was created by cutting vertical or horizontal slots in one flange. Three-dimensional modelling and non-linear static analyses were used to analyse the steel members. The results showed that the strengthening significantly improved the ultimate capacity of the deficient steel members and the effect of a transverse deficiency on the ultimate capacity of the steel members was greater than the effect of a longitudinal deficiency.

Elastic-plastic load-carrying capacity of steel members

The load-carrying capacity of steel structures and members subjected mostly to bending depends in large measure on local stability of their compressed flanges and bending webs in decided cross-sections and areas. Depending on local stability, the elastic or plastic, eventually the elastic-plastic analysis and design can be applied. The actual standards for design of steel structures contain relatively detailed rules for elastic analysis by the elastic theory and for plastic analysis by the plastic theory. The elastic-plastic analysis and design of steel members are meanwhile still problematic from theory, standard and application point of view. The real elastic-plastic behavior of the steel members is complicated strength and stability problem. Therefore, the representative experimental knowledge and results about the real elastic-plastic behavior and mechanisms of failure of the steel members have been very important from the scientific and applied aspects. The author of paper realized in previous time the wide experimental research within the range of this intention. The paper contains selected knowledge and results of the previous experimental-theoretical investigation of the elastic-plastic local stability of the steel members subjected mostly to bending. The adequate slenderness – strain relation and methodology for practical calculation of the elastic-plastic bending load-carrying capacity of the steel cross-sections and members are presented in the paper.

Problems of Cold-Bent Notched C-Shaped Profile Members

Nowadays cold bent steel thermal сold-bent С-profile is widely used in building construction but we still have some little studied questions in the fields of thermal conductivity, air permeability, resistibility and corrosion behavior of the profile. Cold-bent notched С-profile is used for interior exterior panel members. Lengthwise notches made chequerwise in the profile walls increase the distance of heat flow and decrease heat conductivity and eliminate cold bridges that is why the profile is called “thermal profile”. Cold-bent profile made by cold bending requires alternate approach when engineering structures are designed and maintained. The approach means thin walls’ and the profile special form’ impact on the bearing capacity and stability of the structures should be taken into account. In spite of the wide use of cold-bent notched C-profile in building frameworks, we see lack of information on how the notches influence the bearing capacity and stability of structures. There are no official normative documents on calculation and designing of cold-bent notched profile structures. We carry out theoretical and experimental investigations on global buckling and bearing capacity of steel members of C-shaped notched profiles of different cross-sections area. We carry out theoretical and experimental investigations on heat current passing through the thermal profile structure is held with the use of testing bed.

Convergent Stresses at the Adhesive Ends of a Steel Member Strengthened with Carbon Fiber Reinforced Polymer Plates

Recently, repairing or strengthening steel members with externally bonded Carbon Fiber Reinforced Polymer (CFRP) plates has been widely reported. In these reports, some criteria for preventing the debonding of the CFRP plates were proposed. In Japan, although CFRP plates have been employed to enhance steel members that are deteriorating from corrosion attack or fatigue cracks or have been applied to upgrade the load-carrying capacity of steel members, there is no clear standard for preventing the debonding of CFRP plates from steel members. In this study, to assist in determining the design criterion for preventing debonding, we derived and solved dierential equations that calculate the stresses in steel members with CFRP plates under concentrated and uniformly-distributed loads. Further, this paper presents the convergent stresses in the adhesive at the ends of the CFRP plates that were strengthening steel members. The convergent stresses at the adhesive ends are sucient to allow CFRP plates to be used under any load conditions.

Utilizable Capacity of Steel Members of Structures

Utilizable Capacity of Steel Members of Structures