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This study aims to verify whether the reduction factors for the post-fire performance of Grade 10.9 bolts stated in an earlier study at the TU Darmstadt are also valid for shear and combined tension and shear.

Tests on Grade 10.9 bolt sets under combined tension and shear were carried out. The tested bolts were heated and cooled without being stressed by an additional mechanical load before being tested.

The test results show that the reduction factors can also be adopted for bolts under combined tension and shear, but the tension-shear-ratio has an influence on the load bearing capacity.

The post-fire performance of high-strength bolts is of special interest when a building structure is evaluated after an event of fire. In contrast to conventional structural steel, high-strength bolts do not recover their original strength and material properties.

THIS paper deals with semi shear‐resistant panels (incomplete tension fields) subjected to pure shear—as well as combined shear and tension loads. It establishes the stresses in the midplane of the sheet and the loads acting on panel joints.

THE main object of this paper is to help bridge the gap that exists between the scientific knowledge of materials and the practical application of that knowledge to the production technique of sheet‐metal forming. During the past year the Production Research Group of Lockheed's engineering department has given special attention to this important problem and has worked closely with the production departments in an effort to put sheet‐metal forming on a scientific basis. The following discussion is based largely on the work of the Production Research Group, as reported in various references and in papers yet to be published. Mr. William Schroeder and Mr. G. A. Brewer of this group have been particularly helpful to the author in the preparation and editing of the technical material. Because of the scope of the present paper, detailed discussion and analysis of new developments cannot be undertaken; however, such information will be made available as soon as possible in the form of individual papers by those directly responsible for the work.

This paper discusses the microstructures of solder joints and the mechanism of thermal fatigue, which is an important source of failure in electronic devices. The solder joints studied were near‐eutectic Pb‐Sn solder contacts on copper. The microstructure of the joints is described. While the fatigue life of near‐eutectic solder joints is strongly dependent on the operating conditions and on the microstructure of the joint, the metallurgical mechanisms of failure are surprisingly constant. When the cyclic load is in shear at temperatures above room temperature the shear strain is inhomogeneous, and induces a rapid coarsening of the eutectic microstructure that concentrates the deformation in well‐defined bands parallel to the joint interface. Fatigue cracks propagate along the Sn‐Sn grain boundaries and join across the Pb‐rich regions to cause ultimate failure. The failure occurs through the bulk solder unless the joint is so thin that the intermetallic layer at the interface is a significant fraction of the joint thickness, in which case failure may be accelerated by cracking through the intermetallic layer. The coarsening and subsequent failure are influenced more strongly by the number of thermal cycles than by the time of exposure to high temperature, at least for hold times up to one hour. Thermal fatigue in tension does not cause well‐defined coarsened bands, but often leads to rapid failure through cracking of the brittle intermetallic layer. Implications are drawn for the design of accelerated fatigue tests and the development of new solders with exceptional fatigue resistance.

This paper presents the full range sensitivity study of various components of material model on the response of reinforced concrete slabs subjected to central patch loads using non‐linear finite element analysis. A layered degenerate quadratic plate element with five degrees of freedom was employed. Smeared crack model was used with orthogonal cracking. The components considered in this work are: perfectly plastic models versus hardening models, role of crushing condition on collapse load, influence of dowel effect on punching capacity, parametric variation of tension stiffening parameter, parametric variation of degraded shear modulus and the role of yield criterion.

The paper describes an investigation of the stresses due to torsion of a doubly‐symmetrical thin‐walled rectangular box section with four corner spar flanges. The box section was subjected to a pure torque at the free end. The other end of the box section was constrained to remain plane. The shear stresses in the top and bottom skins and in the vertical webs and the direct stresses in the corner spar flanges were measured. The measured values were compared with theoretical predictions using the ‘linear’ and ‘closely spaced rigid diaphragm’ assumptions. The torsional stiffness was also measured and compared with theory. The experimental results show the marked effect of buckling of the skin covering on the stresses in the flanges. They also illustrate the importance of using the secant modulus in calculations.

This paper presents a finite element model for analysis of damaged RC beams strengthened or repaired by externally bonding glass fibre reinforced plastics (GFRP) on the tension side of the beams. The salient features include: (i) the introduction of a thin, six—noded element to simulate behaviour of the concrete/epoxy glue/GFRP interface and )ii( a scheme of loading a virgin RC beam to a prescribed displacement to simulate damage, unloading and then reloading the damaged RC beam fortified by an externally bonded GFRP plate. Results are presented for RC beams repaired by plates of varying thickness and a transmutation of failure mode is noted from classical flexure for the case of external reinforcement in the form of thin GFRP plates to a unique concrete cover rip off failure for thicker GFRP plates and not predicted by the ACI shear strength formula for diagonal tension failure of unplated RC beams of similar geometry.

Design engineers use the term load path to describe, in general terms, the way in which loads path through a structure from the points of application to the points where they are reacted. In contrast, stress trajectories are more clearly identified by the direction of the principal stress vectors at a point. The first author proposed a simple definition of the term load path in 1995 and proposed procedures to determine load paths from two‐dimensional finite element solutions. In this paper, the concept of load paths will be further explored and related to stress trajectories and Michell structures. The insight given when determining the load transfer near a pin‐loaded hole will be demonstrated. In addition a cantilevered beam will be considered and an introduction to plotting load paths in three‐dimensional structures is given.

The purpose of this paper is to develop the method for the calculation of residual stress and enduring deformation of helical springs.

For helical compression or tension springs, a spring wire is twisted. In the first case, the torsion of the straight bar with the circular cross-section is investigated, and, for derivations, the StVenant’s hypothesis is presumed. Analogously, for the torsion helical springs, the wire is in the state of flexure. In the second case, the bending of the straight bar with the rectangular cross-section is studied and the method is based on Bernoulli’s hypothesis.

For both cases (compression/tension of torsion helical spring), the closed-form solutions are based on the hyperbolic and on the Ramberg–Osgood material laws.

The method is based on the deformational formulation of plasticity theory and common kinematic hypotheses.

The advantage of the discovered closed-form solutions is their applicability for the calculation of spring length or spring twist angle loss and residual stresses on the wire after the pre-setting process without the necessity of complicated finite-element solutions.

The formulas are intended for practical evaluation of necessary parameters for optimal pre-setting processes of compression and torsion helical springs.

Because of the discovery of closed-form solutions and analytical formulas for the pre-setting process, the numerical analysis is not necessary. The analytical solution facilitates the proper evaluation of the plastic flow in torsion, compression and bending springs and improves the manufacturing of industrial components.

The paper aims to present an experimental testing program regarding reinforced concrete slabs, with and without shear reinforcement, submitted to punching under both symmetric and eccentric loading. Comparisons between numerical simulations and experimental behaviour results are carried on. The capabilities and limitations of the numerical model to reproduce the brittle punching‐shear failure are discussed.

The paper opted for a performance assessment of a numerical model, comparing FEM results with known experimental tests properly instrumented. Capability of DIANA software to simulate the punching behaviour of slabs is discussed.

The paper demonstrates that the mechanical properties assigned to the element layer containing the bending reinforcement impose the load deflection stiffness behaviour. Good agreement was found between the predicted and the observed deformation behaviour. Nevertheless, the reproduction of the punching ultimate capacity is strongly dependent on the adopted value for the shear retention factor, which appears to be the major decisive parameter.

This paper demonstrates that the smeared crack model based on both the concept of strain decomposition (SD) and total strain with fixed orthogonal cracks approach (TSF) can correctly be used for the analysis of the behaviour of slabs submitted to punching shear.