Analytical calculation of tube confined concrete elements with strengthened cores Oleksandr Palyvoda, Dmytro Yermolenko, Oleksandr Andriichuk, Mindaugas Vaicekauskas and Intars Dicmanis E3S Web Conf., 280 (2021) 03005 Published online: 30 June 2021 DOI: 10.1051/e3sconf/202128003005