H.H. Snijder

New prediction model for failure of steel sheeting subject to concentrated load (web crippling) and bending

Abstract Current design rules for steel sheeting do not give adequate insight in the sheetings structural behaviour and are not always accurate. The current rules use three concepts: ultimate bending moment; ultimate concentrated load; and interaction. This paper presents a new analytical model to predict the ultimate load of first-generation sheeting under practical loading conditions. These practical conditions are defined by the ratios between bending moment and concentrated load as occurring in practice. Comparisons between the new model and experiments indicate that the new model reaches approximately the same accuracy as the design rules. The new model provides more insight in the structural behaviour of the sheeting and uses only one concept for determining failure. The new model is based on two existing models. Namely an analytical model developed in 1995 by Vaessen (On the elastic web crippling stiffness of thin-walled cold-formed steel sections, Graduate Thesis TUE-BKO-95-17, Eindhoven University of Technology, The Netherlands) to predict the local web crippling deformation and a solution of Marguerres (Zur Theorie der gekrummter Platte grosser Formanderung. Proc. Fifth. Int. Congress Appl. Mech., p. 93) simultaneous differential plate equations included in a book by Murray (Introduction to the Theory of Thin-walled Structures, Oxford Engineering Science Series 13, Clarendon Press, Oxford).

Combined web crippling and bending moment failure of first-generation trapezoidal steel sheeting

Current design rules for cold-formed trapezoidal sheeting, which predict sheeting failure for an interior support, do not provide sufficient insight into the sheeting behaviour, and can differ up to 40% in their predictions. To develop a new design rule, this article presents new experiments in which first-generation sheeting behaviour is studied for practical situations. The experiments show that after ultimate load, three different post-failure modes arise. Finite element models were used to simulate the experiments. Studying stress distributions with finite element simulations, it can be seen that there are only two ultimate failure modes at ultimate load. One of these ultimate failure modes is probably not relevant for practice. A mechanical model has been developed for the other ultimate failure mode. This model performs as well as the current design rules, and it provides insight into the sheeting behaviour.

Local Buckling of Fire-Exposed Aluminum Members: New Design Model

Design models for local buckling of fire-exposed aluminum sections are currently lacking. Based on analyses with validated finite-element models, this paper investigates local buckling of extruded sections with stress-strain relationships representative for fire-exposed aluminum alloys. Due to the fact that these stress-strain relationships are more curved than at ambient temperature, existing design models developed for ambient temperature cannot be used for fire design. This paper presents a new design model for local buckling under fire conditions. The study concludes that the local buckling resistance decreases less fast than the plastic capacity at increasing temperature. This is mainly due to the fact that the ratio between the modulus of elasticity and the 0.2% proof stress increases with increasing temperature for structural aluminum alloys.

High-Rise Structures with Belt Bracing Subject to Lateral Load

This paper presents simple methods of analysis for preliminary design of high-rise structures comprising reinforced concrete shear walls or steel trussed frames with a perimeter belt bracing structure consisting of steel trusses, subjected to horizontal loading. The methods are based on the analysis of facade rigger braced structures where horizontal steel trusses (web riggers), located in the two end facades (web frames), are positioned in a direction parallel to the lateral loading on the building. Perpendicular to the horizontal load additional horizontal steel trusses in the wind and lee sides of the building, “flange trusses”, complete the belt bracing structure. The method is focused on the contribution of the flange trusses to the lateral stiffness of the structure. The shear-lag due to differential strain in the flange frame columns along the wind and leeward facades is caused by bending and racking shear deformations in the flange trusses and is taken into account. In an approximate method the flange columns are replaced by a continuous medium of equivalent axial stiffness, i.e. a beam on an elastic foundation. The proposed methods of analysis, for use in the initial stages of the structural design of proposed tall buildings, offer simple and rapid means of establishing the influence of belt structures on horizontal deformations of the high-rise structure and internal forces.

Experimental work and FEM-calculations on the interaction of local buckling modes in aluminium sections

The extrusion manufacturing process of aluminium allows protiles with a large variety of cross-sections. If these are thin-walled. cross-sectional instability miszht occur, which is caused by interaction of local buckling modes of connecting plate elements. To investigate this phenomenon. an extensive set of experiments is performed on uniformly compressed aluminium RHS-sections at Eindhoven University of Technology. In-plane and out-of-plane plate detormations are visualised using a so-called ESPI-laser system. The tests are used to alidate a finite element model. which results are presented as welt. In a subsequent research this model will he used to analyse the failure modes of more complex sections.

Plastic collapse load of crown-hinged steel circular arches : a theoretical method

For construction purposes and to avoid detrimental influences of foundation settlements arches are not always made from a single arch-rib but are built by connecting two curvilinear elements at the crown with a hinge. These arches are also known as crown-hinged arches. This paper presents an analytical procedure to approximate the plastic collapse load of circular crown-hinged steel arches. The development of the analytical method employs the lower- and upper bound theorem of plastic theory and the kinematic admissibility requirements. The influence of normal forces on the plastic moment capacity of the steel section is taken into account. The plastic collapse load is obtained by an iterative method as there is a non-linear relationship between the acting loads and the reduction of the plastic moment capacity due to normal forces. Through a comparison with earlier studies and finite element analyses, it is concluded that the proposed iterative method gives good results.

Composite action of steel frames and precast concrete infill panels with corner connections – Part 1 : experiments

When precast concrete infill panels are connected to steel frames at discrete locations, interaction at the structural interface is neither complete nor absent. The contribution of precast concrete infill panels to the lateral stiffness and strength of steel frames can be significant depending on the quality, quantity and location of the discrete interface connections. This paper presents preliminary experimental results of an investigation into the composite behaviour of a square steel frame with a precast concrete infill panel subject to lateral loading. The panel is connected at the corners to the ends of the top and bottom beams. The corner frame-to-panel-connection between steel beam and concrete panel consists of two parts. A T-section with five achor bars welded to the top of the flange is cast in at the panel corner at a forty five degree angle. The triangularly shaped web of the T-section is reinforced against local buckling with a stiffener plate. The web is bolted to a triangular gusset plate which is welded to the beam flange. This way the connection acts either in tension or compression. Experimental pull-out tests on individual connections allowed their load deflection characteristics to be established. A full scale experiment was performed on a one-storey one-bay 3 by 3 m infilled frame structure which was horizontally loaded at the top. The yielding level, ultimate strength and lateral stiffness compared favorably with results from a previous test with a similar frame panel connection. A numerical analysis of the infilled frame structure with corner connections is presented in an accompanying paper.