Abstract: To investigate seismic performance of beam-column knee joints, four full-scale reinforced concrete beam-column knee joints, which were fabricated to simulate those in as-built RC frame buildings designed to ACI 318-14 and ACI-ASCE 352R-02, were tested under reversed cyclic loading. In the experimental programme, particular emphasis was given to the effect of horizontal reinforcement (in format of inverted U-shape bars) on the shear strength and ductility capacity of knee joints. Test results are compared with those predicted by four seismic design codes, including ACI 318-14, EC8, NZS3101 and GB50010. It is seen that the current design codes of practice cannot accurately predict the shear strength of seismically designed knee joints.
Abstract: Knee joints, the beam column connections found at the roof level of a moment resisting frame buildings, are inherently different from conventional interior and exterior beam column connections in the way that forces from adjoining members are transferred into joint and then resisted by the joint. A knee connection has two distinct load resisting mechanisms, each for closing and opening actions acting simultaneously under reversed cyclic loading. In spite of many distinct differences in the behaviour of shear resistance in knee joints, there are no special design provisions in the major design codes available across the world due to lack of in-depth research on the knee connections. To understand the relative importance of opening and closing actions in design, it is imperative to study knee joints under varying shear stresses, especially at higher opening-to-closing shear stress ratios. Three knee joint specimens, under different input shear stresses, were designed to produce a varying ratio of input opening to closing shear stresses. The design was carried out in such a way that the ratio of flexural strength of beams with consideration of axial forces in opening to closing actions are maintained at 0.5, 0.7, and 1.0, thereby resulting in the required variation of opening to closing joint shear stress ratios among the specimens. The behaviour of these specimens was then carefully studied in terms of closing and opening capacities, hysteretic behaviour, and envelope curves to understand the differences in joint performance based on which an attempt to suggest design guidelines for knee joints is made emphasizing the relative importance of opening and closing actions. Specimens with relatively higher opening stresses were observed to be more vulnerable under the action of seismic loading.
Abstract: Insider abuse has recently been reported as one of
the more frequently occurring security incidents, suggesting that
more security is required for detecting and preventing unauthorised
financial transactions entered by authorised users. To address the
problem, and based on the observation that all authorised interbanking
financial transactions trigger or are triggered by other
transactions in a workflow, we have developed a security solution
based on a redefined understanding of an audit workflow. One audit
workflow where there is a log file containing the complete workflow
activity of financial transactions directly related to one financial
transaction (an electronic deal recorded at an e-trading system). The
new security solution contemplates any two parties interacting on
the basis of financial transactions recorded by their users in related
but distinct automated financial systems. In the new definition interorganizational
and intra-organization interactions can be described
in one unique audit trail. This concept expands the current ideas of
audit trails by adapting them to actual e-trading workflow activity, i.e.
intra-organizational and inter-organizational activity. With the above,
a security auditing service is designed to detect integrity drifts with
and between organizations in order to detect unauthorised financial
transactions entered by authorised users.