Nowadays,More and more pepole like to use bamboo poles ( http://www.chinabamboogarden.com/bamboo-pole-cane-stake.asp ) to build fence,gazebos,pergolas and more structures at their garden,spa and patio,although bamboo are also known for their durability,they can last for twenty years if pepole make a proper maintenance.  but how to maintain poles durability and  lasting longer ?

You  need to ensure that they don't come in direct contact with the ground. Direct contact to ground will make poles decayed ,same reason, you must seal exposured end or cut bamboo at the knots at the top end

In order to avoild insects and mildew,you need to get rid of sweet in bamboo poles ; Bamboo poles should be bleaching treated and naturally dried and then cured before it is ready to be sold. meanwhile,the wax was also removed ,so a regualr finishing process is neccessory, It would be better if you put bamboo poles impregnated into outdoor plant oil

Any outdoor natural product will start to break down over time. Bamboo is no different. Eventually it will go to dry out and shrink during sunshine and dry climate,and swell out when suck moisutre during humidity weather ; which cause cracking  due to exposure to the weather. The only way to preserve it is to fasten by ropes when the poles appears cracking