Bolt tensile failure

Blast loaded structures produce high reaction loads at column supports. This usually requires substantial base plates as well as high capacity anchor bolts. Achieving full anchorage of these bolts is of primary importance and will usually require headed bolts or plates at the embedded end of the bolts to prevent pullout. When anchor bolts are securely anchored into concrete, the failure mechanism is a ductile, tensile failure of the bolt steel. Insufficient edge distance or insufficient spacing between bolts results in a lower anchorage capacity and a brittle failure mode. 

Bearing, shear-out, pin shear, and bypass tensile failure prediction (washers and bolt tightening)... 

Mechanical failures occur when the part is exposed to some t5q)e of force that exceeds its capability. A part may be exposed to three different t5q)es of forces tensile, compression, and vacuum-generated stresses. Many processes require super- or subatmo-spheric pressure. In a fluoropol5mier-Iined vessel or a stand-alone vessel at elevated pressure, the walls are subjected to tensile stress. Compression stress develops in parts such as seals and gaskets where force is applied to the part, for instance, by placing it between bolted flanges. Vacuum can be a permanent or transient feature of a process and subjects a part to complex forces which could be a combination of tensile and compression. 

In this section, the effects of clearance on the damage response of the C1 C1 C1 double-lap joint (i.e. a control case) and the C3 C3 C1 double-lap joint (i.e. a worst case scenario in the sense that all the load is initially carried by one bolt) are investigated. The progression of damage in the joints is shown at applied load levels of 10,30 and 50 kN for the four different failure modes considered, i.e. tensile matrix failure compressive matrix failure tensile fibre failure and compressive fibre failure. These load levels were chosen so that the damage could be tracked fiom initiafion up to the point of extensive damage. 

A more recent report on the effects of high tensile bolt failures on the charge pan structure recommended further Investigation Intd the condition of the charge pan bolts This outlined a need to develop a non-destructive, socket headed bolt testing technique, to complement the computer model predictions (Ref 1) ... 

P. McIntyre The Effects of High Tensile Bolt Failures on the... 

Consider the web-flange splice shown in Figure 5.14. The fasteners are subjected to shear. Assume that the flange splice transfers the bending moment through tensile and compressive forces and that the web splice carries the transverse shear. The composite beams are made from fibre reinforced composite material. As the joint is loaded, the flanges and web move and the bolts contact portions of the holes. As the load is increased, failure of the joint may occur in different modes, i.e. net-section, bearing, and shear out. 

During investigation of the fly ash silo failure described above (2.5), it was discovered that less than 1% of the bolts recovered had the specified marking on their head, and none of these were used in the critical vertical seams. Strength tests on these incorrect bolts revealed that some had tensile strengths less than the minimum required for the specified bolts. 

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