The interventricular septum, which flattens and inverts in conditions such as pulmonary hypertension, is considered by many to be an unstressed membrane, in that its position is assumed to be determined solely by the transseptal pressure gradient. A two-dimensional finite element model was developed to investigate whether compression and bending moments (behavior incompatible with a membrane) exist in the septum during diastole under abnormal loading, i.e., pulmonary artery (PA) constriction. Hemodynamic and echocardiographic data were obtained in six open-chest anesthetized dogs. For both control and PA constriction, the measured left ventricular and right ventricular pressures were applied to a residually stressed mesh. Adjustments were made to the stiffness and end-bending moments until the deformed and loaded residually stressed mesh matched the observed configuration of the septum. During PA constriction, end-bending moments were required to obtain satisfactory matches but not during control. Furthermore, substantial circumferential compressive stresses developed during PA constriction. Such stresses might impede septal blood flow and provoke the unexplained ischemia observed in some conditions characterized by abnormal septal motion.

Modelling load bearing in diarthrodial joints is challenging, due to the complexity of the materials, the boundary and interface conditions and the geometry. The articulating surfaces are covered with cartilage layers that are filled with a fluid that plays a major role in load bearing [Mow, V.C., Holmes, M.H., Lai, W.M. (1984) “Survey article: fluid transport and mechanical properties of articular cartilage: a review”, Journal of Biomechanics 17(5), 377–394]. Researchers have tended to approximate joint geometry using axisymmetry [Donzelli, P.S., Spilker, R.L., Ateshian, G.A., Mow, V.C. (1999) “Contact analysis of biphasic transversely isotropic cartilage layers and correlations with tissue failure”, Journal of Biomechanics 32, 1037–1047], often with a rounded upper articulating surface, creating a form of Hertz problem [Donzelli, P.S., Spilker, R.L., Ateshian, G.A., Mow, V.C. (1999) “Contact analysis of biphasic transversely isotropic cartilage layers and correlations with tissue failure”, Journal of Biomechanics 32, 1037–1047]. However, diarthrodial joints (shoulder, hip and knee) are equipped with peripheral structures (glenoid labrum, acetabular labrum and meniscus, respectively) that tend to deepen the joint contact and thus cause initial contact to be established at the periphery of the joint rather than “centrally”. The surface geometries are purposefully incongruent, and the incongruency has a significant effect on the stresses, pressures and pressure gradients inside the tissue. The models show the importance of the peripheral structures and the incongruency from a load-bearing perspective. Joint shapes must provide a compromise between demands for load-bearing, lubrication and the supply of nutrients to the chondrocytes of the cartilage and cells of the peripheral structures. Retention and repair of the functionality of these peripheral structures should be a prime consideration in any surgical treatment of an injured joint.

Carbon fiber–reinforced polymer (CFRP) laminates are widely used in strengthening reinforced concrete slabs, beams, and columns. However, the application of this advanced composite material to strengthen steel structures is still evolving, and more research is needed to facilitate deployment. This paper presents the results of an experimental program aimed at investigating the behavior of steel columns subject to eccentric loading and strengthened using bonded high-modulus CFRP laminates. Thirty hollow steel section (HSS) column specimens ($48\times 48\times 2\mathrm{mm}$ ) were eccentrically loaded to failure using load eccentricity values of 25, 50, and 100 mm. The efficiency of bonding the CFRP laminates to the HSS column in enhancing the column’s capacity was evaluated for different column slenderness ratios ($kL/r$ ) ranging between 68 and 131. Depending on the slenderness ratio and the load eccentricity, it was found that the increase in axial load capacity of the CFRP-strengthened columns ranged between 40 and 107%, and the increase in the ultimate moment ranged between 34 and 135%; the maximum increase in a column’s capacity corresponded to the medium column slenderness ratio. Two successive failure modes for the strengthened HSS columns were encountered: CFRP laminates debonding and flexural buckling of the column. Flexural buckling was the dominant mode of failure for all the unstrengthened columns (control specimens). On the other hand, debonding of CFRP laminates was observed either before or after flexural buckling for the strengthened columns depending on the load eccentricity value and the slenderness ratio.

During the process of concrete hardening, temperature profiles show gradual non-linear distributions due to the generation of heat development by cement hydration. At early ages, this distribution can have an influence on crack evolution, especially in mass concrete such as that used in gravity dams. It is thus important to study the factors affecting the amount of heat generated in the hydration process and minimise it as much as possible to prevent the generation of undesired cracks through the dam's body. Coupled thermal-stress finite-element analysis, which also considers the stages of construction, has been performed on a concrete gravity dam (Muzdalifa dam, KSA) to determine the impact of changing the time intervals in concrete placing schedule on the thermal/stress response of the dam. The significance of time, material and environmental factors has been scrutinised: the investigated parameters were the concrete casting construction schedule, the cement content and the ambient temperature. The investigation also explored the effect of introducing water pipe cooling system on the generated temperature and induced stresses, and then recommends an effective scheme for pipe cooling.

Behaviour of precast-prestressed hollow core slabs has been extensively studied when these slabs are subjected to positive bending moments, a practical application typical of hollow core slabs. However, in many projects it may be required to have an overhanging part of the roof to act as a cantilever. In doing so, and using precast-prestressed hollow core slabs, the slabs would be subjected to negative moments, atypical for hollow core slabs. In this paper, the behaviour of precast-prestressed hollow core slabs is experimentally investigated when they are subjected to negative bending moments. A proposed strengthening detail to increase the negative moment resistance of hollow core slabs using bonded carbon fibre reinforced polymer (CFRP) strips is presented. The CFRP strips were bonded to the top side of full-scale precast-prestressed hollow core slabs in the negative moment zone in different configurations. In two of the tested slabs the bond between the prestressing strands and the concrete was initially broken (during casting of the slabs) in the negative moment zone. The slabs with the bonded CFRP strips were tested to failure and the load–deflection behaviour was recorded. The results of the tests are presented and the strength enhancement of the hollow core slabs using the proposed technique is reported. The increase in the negative moment resistance of the CFRP-bonded hollow core slabs experimentally determined is also compared with the CSA-S806-02 prediction for the moment resistance of concrete elements with bonded CFRP strips.Key words: carbon fibre reinforced polymer (CFRP) strips, hollow core slab, flexure strengthening, prestressed concrete, precast slabs, prestressing strands.