Forces2018 Presentation:The Assessment Of Pile Group Integrity Due To Pile Ec...azhar ahmad
The mode of driving precast reinforced concrete piles on site is without doubt among the most ‘error prone’ trades of a construction process. The short comings of driving pre designated piles at pin point accuracy at exactly the correct position on the ground has given rise to the caption of ‘pile eccentricity’ of nearly all individual piles within a pile group.
This then raises questions of integrity or how safe and reliable are pile caps that has been designed earlier with zero pile eccentricities. Questions of how much an eccentricity limit can be allowed for each pile or rather pile group arrangements such that previous pile cap designs are still safe and applicable has to be addressed. Thus one of the aims of this study is to evaluate the maximum allowable eccentricity of several common pile group arrangements. Results of this study indicates that the norm of adopting a maximum allowable eccentricity value of 75 mm for each individual pile irrespective of pile size, pile working load, pile spacing & column loads is quite misleading and may result in an unsafe pile group performance! Rather, results from this study suggests that the critical factor is not the eccentricity of individual piles but the overall net pile group eccentricity. This causes eccentric moments to act in the pile group which in turn governs the redistributed load to each individual pile within the pile group. This redistributed loads are then compared to the pile safe working load to establish a ‘Pass-Fail’ criteria.
Forces2018 Presentation:The Assessment Of Pile Group Integrity Due To Pile Ec...azhar ahmad
The mode of driving precast reinforced concrete piles on site is without doubt among the most ‘error prone’ trades of a construction process. The short comings of driving pre designated piles at pin point accuracy at exactly the correct position on the ground has given rise to the caption of ‘pile eccentricity’ of nearly all individual piles within a pile group.
This then raises questions of integrity or how safe and reliable are pile caps that has been designed earlier with zero pile eccentricities. Questions of how much an eccentricity limit can be allowed for each pile or rather pile group arrangements such that previous pile cap designs are still safe and applicable has to be addressed. Thus one of the aims of this study is to evaluate the maximum allowable eccentricity of several common pile group arrangements. Results of this study indicates that the norm of adopting a maximum allowable eccentricity value of 75 mm for each individual pile irrespective of pile size, pile working load, pile spacing & column loads is quite misleading and may result in an unsafe pile group performance! Rather, results from this study suggests that the critical factor is not the eccentricity of individual piles but the overall net pile group eccentricity. This causes eccentric moments to act in the pile group which in turn governs the redistributed load to each individual pile within the pile group. This redistributed loads are then compared to the pile safe working load to establish a ‘Pass-Fail’ criteria.