Source google image: http://www.moinsde170.com/blog/wp-content/uploads/2012/04/ES_VUE1_RDC-1a.jpg
Www.terrasse-bois.info/calcul-de-la-portee-d-une- poutre.html
Source google image: http://www.moinsde170.com/blog/wp-content/uploads/2012/04/ES_VUE1_RDC-1a.jpg