Original Research Article Structural behaviour of prestressed stayed columns with single and double cross-arms using normal and high strength steel Joao Pedro Martins * , Ashkan Shahbazian, Luís Simões da Silva, Carlos Rebelo, Rui Simões Institute for Sustainability and Innovation in Structural Engineering (ISISE), Civil Engineering Department, University of Coimbra, Coimbra, Portugal 1 1. Introduction Nowadays, designing long span structures is a common solution by structural engineers which means using long (slender) columns. However, two important parameters should be considered: (a) slender columns are a practical solution when self-weight is not dominant and (b) depending on the design, global buckling often happens in the elastic range and using high strength steel (HSS) may not improve the load carrying capacity. These issues are known for a few decades and since then researchers are trying to find solutions to avoid them. One solution to improve the load carrying capacity of slender columns is to add prestressed cables and cross-arms as they provide restraints which reduce the slenderness of the column. Such columns are called prestressed stayed columns (PSSC). Fig. 1 illustrates a typical PSSC used in practice. PSSC have been investigated experimentally, numerically and analytically by researchers since 1960 [12–19], a thorough literature review being found in Serra et al. [1]. a r c h i v e s o f c i v i l a n d m e c h a n i c a l e n g i n e e r i n g 1 6 ( 2 0 1 6 ) 6 1 8 – 6 3 3 a r t i c l e i n f o Article history: Received 17 December 2015 Accepted 5 April 2016 Available online Keywords: Prestressed stayed columns High strength steel Cabled columns Buckling High slender column a b s t r a c t One solution to improve load carrying capacity of slender columns is to add prestressed cables and cross-arms as they provide additional restraints along the length. Such columns are called prestressed stayed columns (PSSC). This solution is very effective, but there are no experimental results on long columns which is a practical case for such columns. This paper presents the results of an experimental study on 18 m PSSC with single and double cross- arms along the length and using normal and high strength steel. In total, 77 tests were carried out to investigate the structural behaviour of such systems and improvements made by using high strength steel and stay systems. The results in this paper provide detailed data on the behaviour of realistic PSSC which was not available before and highlight the advantages of the using high strength steel in such systems. # 2016 Politechnika Wroclawska. Published by Elsevier Sp. z o.o. All rights reserved. * Corresponding author at: Civil Engineering Department, University of Coimbra, Rua Luis Reis Santos, Polo II, 3030-788 Coimbra, Portugal. Tel.: +351 239 797 259. E-mail address: jpmartins@dec.uc.pt (J.P. Martins). 1 http://www.dec.uc.pt/. Available online at www.sciencedirect.com ScienceDirect journal homepage: http://www.elsevier.com/locate/acme http://dx.doi.org/10.1016/j.acme.2016.04.004 1644-9665/# 2016 Politechnika Wroclawska. Published by Elsevier Sp. z o.o. All rights reserved.