Abstract: A ripple down rules knowledge based system for generating an output conclusion in response to an input case, the system including a database arranged to receive and store a plurality of conclusions and a plurality of rules, each new conclusion added to the database being associated with a previously stored conclusion as a refinement of the previously stored conclusion and each new conclusion added to the database being associated with a rule, input mechanism for facilitating input of a case, and output mechanism for outputting at least one previously stored conclusion in response to the input case, the system being arranged such that when multiple identical conclusions are returned by the system in response to an input case and a new conclusion associated with the input case is added as a refinement of the identical conclusions, a list of cornerstone conflict cases associated with all of the identical conclusions is generated, and the system being arranged to receive an input rule indicative of a difference b

Abstract: A precast concrete beam is supported at its end by columns via the agency of retractable hanger arrangements preferably located in cavities at the upper ends of the beam. Each hanger arrangement includes a hanger member which is movable in the cavity from a retracted position within the cavity through a hanger eye device to an extended position in which the hanger member engages the eye device at an upper central portion of the hanger member and in which the hanger member extends in cantilever manner into a recess defined in the adjacent column. In its extended position, the hanger member has its opposite ends supported on bearing plates located in the cavity and in the recess. The hanger eye device is structurally tied into the beam for carriage and transfer to the beam of the support forces for the beam and of forces arising from loads applied to the beam in use.

Abstract: A precast reinforced concrete exterior wall panel is connected in a building between supporting columns by connectors which enable the panel to carry lateral shear loads in the building. As precast, the panel includes encased but not embedded steel straps which extend end to end in the panel for carrying loads applied to the panel ends via the connectors. The connectors include face abutting mating moieties. The mating faces of each moiety defines a regularly repeating grid pattern of projections and recesses so arranged that the moieties are engageable in face abutting relation with the projections of each engaged in the recesses of the other at any of a plurality of discrete relative positions of the moieties. When so engaged and clamped together, the connector moieties cooperate to carry shear loads across the plane of the mated faces. One moiety is connected to a panel strap end and the other is embedded in or affixed to an adjacent column.