NEW APPROACHES ON THE ARCHAIC TRADE IN THE NORTH‐EASTERN IBERIAN PENINSULA: EXPLOITATION AND CIRCULATION OF LEAD AND SILVER

A wide‐ranging study based on compositional and isotopic analyses of minerals and manufactured objects from the north‐eastern Iberian Peninsula and their respective archaeological and cultural contexts demonstrates significant lead mineral exploitation in the El Priorat area (Tarragona province) linked to Phoenician trade (seventh–sixth centuries BC). This exploitation continued, despite losing intensity, until the Romanization of the territory. Our project also aims to determine the nature and origin of the lead and silver supply in the northern Iberian territory surrounding the Phocaean enclave of Emporion, especially with regard to the demands of the colonial mint. The behaviour pattern of the circulation of lead, silver and copper in Catalonia in the period studied indicates a plurality of contemporary supply sources, although, at least from the fifth century BC onward, minerals and metals from the south‐eastern Iberian Peninsula take on considerable importance.     

SEISMIC DESIGN OF BASE-ISOLATED STRUCTURES USING CONSTANT STRENGTH SPECTRA

This paper presents the concept of constant strength design spectra for the design of base-isolated structures; particularly those structures using isolators with a bilinear hys-teretic behaviour when subjected to dynamic loading. The constant strength design spectra relate peak accelerations, velocities, displacements and effective isolated natural periods for bilinear systems with a given yield strength and post yield stiffness. Constant strength design spectra could be useful for the design of base isolators with bilinear hysteretic behaviour, as these devices can be designed for fixed yield strength and post yield stiffness. The concept of constant strength design spectra and its application for the design of base isolated structures is illustrated with case studies of specific structures.