Plain and threaded bearing strengths for the design of bolted connections with pultruded FRP material

Presented are results from testing 28 batches of 5 or 10 nominally identical specimens to characterise the laterally unrestrained pin-bearing strength when bolting is with and without thread. For the test series flange material is taken from a 254x254x9.53 mm Pultex® SuperStructural 1525 series shape. Strengths are measured with the Fibre Reinforced Polymer (FRP) material oriented at either 0° or 90° to the direction of pultrusion. Four steel bolt sizes of M10, M12, M16 and M20 are used, and when threaded there are different standard teeth (pitch) geometries. To remove this variable in a comparison with plain pin strengths a unique test series of 12 batches was carried out with three non-standard thread profiles. The effect on pin-bearing strength of having a threaded bolt is evaluated using mean and characteristic strengths, the latter determined in accordance with EN 1990. A key finding is that the proposed reduction factor of 0.6 in a forthcoming American LRFD standard to calculate a thread characteristic strength from the plain value is acceptable. Other findings are important to the determination of pin-bearing strength, and to us having knowledge and understanding to prepare a universal design procedure for resistances in bolted connections when the mode of failure is bearing.

[1]  Geoffrey Turvey.  Single-bolt tension joint tests on pultruded GRP plate — effects of tension direction relative to pultrusion direction , 1998 .

[2]  J. Toby Mottram.  Determination of pin-bearing strength for the pin-design of bolted connections with standard pultruded profiles , 2009 .

[3]  L. Bank.  Composites for Construction: Structural Design with FRP Materials , 2006 .

[4]  J. Toby Mottram.  Does Performance Based Design with Fibre Reinforced Polymer Components and Structures provide any new Benefits and Challenges , 2011 .

[5]  Behrouz Zafari,et al.  Pin-bearing strengths for bolted connections in fibre-reinforced polymer structures , 2011 .

[6]  I. El-Sonbaty,et al.  Machinability analysis in drilling woven GFR/epoxy composites: Part I – Effect of machining parameters , 2010 .

[7]  Youjiang Wang.  Bearing Behavior of Joints in Pultruded Composites , 2002 .

[8]  Geoffrey Turvey,et al.  Bolted connections in PFRP structures. , 2000 .

[9]  Srinivasa D. Thoppul,et al.  Mechanics of mechanically fastened joints in polymer–matrix composite structures – A review , 2009 .

[10]  J. Park,et al.  STRUCTURAL BEHAVIOR OF PFRP CONNCETION WITH SINGLE BOLT , 2011 .

[11]  J. Mottram,et al.  Numerical evaluation of pin-bearing strength for the design of bolted connections of pultruded FRP material , 2017 .

[12]  J. Toby Mottram,et al.  Design guidance for bolted connections in structures ofpultruded shapes: gaps in knowledge , 2009 .

[13]  Geoffrey Turvey,et al.  Physical test data for the appraisal of design procedures for bolted joints in pultruded FRP structural shapes and systems , 2003 .