Prediction of Net-Tension Strength for Multirow Bolted Connections of Pultruded Material Using the Hart-Smith Semiempirical Modeling Approach

Presented in this paper is a study to show that the Hart-Smith semiempirical modeling approach can be used to predict the net-tension strength of multirowed bolted connections of pultruded material. Using the original 1987 paper by Hart-Smith a strength equation is developed for the specific connection configuration of two rows with a centrally placed steel bolt. The reported equation can be directly used for the two orientations of material that have the tension load parallel or perpendicular to the direction of pultrusion. Using experimental measurements for material properties and single-bolted connections from Rosner’s 1992 work and the open-hole tension strengths from Turvey and Wang’s 2003 paper, representative values to the modeling parameters in the strength equation are established. For model verification a comparison is made between theoretical and experimental strengths, using 17 test results from Hassan et al.’s 1997a work. Only two of the 17 experimental-to-theory strength ratios are $<1.0$ , and only one of these two could be said to have predicted unsafe net-tension strengths. With none of the ratios exceeding 1.2, it is seen that the simple and versatile modeling approach gives very acceptable predictions. To determine the modeling parameters that will enable the Hart-Smith approach to be in a load resistance factor design standard there is a need for a comprehensive series of strength tests, for net-tension failure with filled- and open-holes, that covers the complete range of multirowed bolted connections that is to be permitted by the standard.