II. Read, translate and retell the text “Seismic Response of Friction Jointed Precast Panel Shear Walls”

Examination Question – Paper № 19

II. Read, translate and retell the text “Architectural Concept of the Pedestrian Bridge in the Exhibition Centre”.

Examination Question – Paper № 18

A total of 158 components weighing 115 tons contribute to the eye-catching design of the pedestrian bridge that links the two major exhibition areas of the Central Exhibition Centre. Bisected by a road, the Central Exhibition Centre is divided into the two exhibition areas completed in two different stages.

Design criteria were established for the bridge, based on its siting: net height (from road surface to lower edge of bridge), 5.2 m; length of main span, 14,7 m; width, 2.8 m; two points access at each end; the appearance should be an expression of plastic art that would contrast with the center’s steel building.

Four competing schemes were submitted, two of steel and two of concrete. The two concrete submittals were chosen for further preliminary consideration:

A. An independent pretension prestressed concrete segmental I-beam supporting a precast/cast-in-place concrete deck for the main span, and a reinforced concrete structural system for the bridge approaches.

B. Precast, prestressed concrete panels functioning as both main beam and railing panel for the bridge span; a precast, prestressed concrete structural system forming the approaches to the bridge.

Based on the cost estimates, Scheme B was the more economical structure, its cost being 10 percent less than that of Scheme A. There were physical advantages as well. Because the main span slab was supported between the railing panels, the slab level was 1 m lower than in Scheme A. In addition, the total length of the approaches was shorter than Scheme A.

The Central Exhibition Centre buildings are of structural steel with colorful finishes. Choosing concrete for the pedestrian bridge was aesthetically beneficial because the concrete would stand out in sharp contrast to the steel buildings, helping to make the bridge a focal point of the exhibition centre.

Зав. кафедри ТіППГіРМ М.М. Барков

Earthquake ground motions cause structures to respond in proportion to the amount of the seismic input energy. Efficient control and dissipation of this energy is necessary to ensure that buildings escape serious damage. In modern philosophy of earthquake resistance, ductility has been accepted as the prime design criterion. However, the limited inherent ductility of precast concrete large panel structures has led to doubts concerning their capacity for energy absorption. Furthermore, the general higher stiffness associated with such buildings over conventional framed systems invites higher inertial forces, thereby placing greater demands on strength and ductility.

These concerns, coupled with a general lack of data on the seismic response of large panel buildings, have contributed to limiting the use of large panel construction in the seismically active zones. Indeed, the widespread destruction of precast concrete buildings during the 1988 earthquake in Armenia provides dramatic evidence not only for the need to ensure adequate design and good quality in construction but also for the additional need to examine possible means to improve the seismic resistance of such structures.

The concept of using friction type mechanical connectors along vertical joints was introduced in order to minimize damage in precast panel structures. The scientists performed analytical studies on the seismic response of coupled large panel shear walls to determine the effectiveness of employing limited slip bolted friction type mechanical connectors located along the vertical joints. It was demonstrated that walls coupled through such limited slip bolted connectors could be tuned to provide optimum response by varying the connector shear slip load. Thus, these connectors were shown to act both as safety valves in releasing load on the vertical connections and as dampers to reduce the overall response of the structure.

Зав. кафедри ТіППГіРМ М.М. Барков

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