Double-ended threaded bolt with small hexagonal head on one side.

Abstract

This product is a double-threaded bolt with a small hexagonal head on one side, used in the attachment of through-posts and girders or waist beams in conventional wooden buildings. It is fitted and tightened with the internal female thread of a lag screw bolt with internal threads on both ends, which has a lag screw shape with high and large threads, a wide thread pitch, and a thread portion that bites into the wood material, and then the through-post and girder are tightened and fixed with a washer and a hexagonal nut. This product is used when attaching through-posts to beams by processing in two directions or three directions in a T-shape and tightening and fixing with bolts. In light of the fact that the long tenon processing of the girders results in a considerable reduction in the cross-sectional area of ​​the columns, which is a major cause of building collapse, such as "back-bending" depending on the magnitude and severity of shaking during an earthquake, this method eliminates the long tenon processing of the girders on the mounting surface of the through-columns, minimizing the reduction in cross-sectional area, and enables the integrated rigidity of the through-columns and girders. This high-rigidity joint between columns and girders is achieved by using lag screw bolts with internal threads at both ends and double-threaded bolts with small hexagonal heads on one end, with the girders in contact with the mortise and tenon processing of the girders processed into the through-columns, and the double-threaded bolts with small hexagonal heads on one end are pre-installed inside the mounting girders. The bolt is secured to the inside of the column by fitting and fastening it with the internal female threads of a lag screw bolt with internal threads at both ends. After fastening, the bolt is secured by inserting a tightening nut through a countersunk hole in the top and bottom of the beam, and then fastening it with a hexagonal nut via a spring washer. The body shape of the double-threaded bolt with a small hexagonal head on one end is such that a small hexagonal head of a certain shape extends from one end. The diameter of the threads between the peaks of the hexagonal head is slightly smaller than the diameter of the internal threads of the hexagonal nut, making it easier to pass the nut through when fitting the external thread portion of the double-threaded bolt with a small hexagonal head on one end with the washer and hexagonal nut for later tightening. It is characterized by having a small hexagonal head, an internally formed external thread portion of a certain outer diameter and length on the opposite side, then an intermediate unthreaded body portion of the same diameter, and the end has the shape of an external thread portion of a certain outer diameter and length, the thread pitch and outer diameter of the threaded portions formed on both sides are equal, and the overall length takes into account the position of the nut tightening portion machined into the top and bottom of the girder, the so-called length from the end of the girder that is in contact with the column surface to the same position, and the length for fitting with the internal female thread of the internal threaded lag screw bolt at both ends, the size of the diameter of the through column,This double-threaded bolt with a small hexagonal head on one end can be adapted to various lengths and outer diameters depending on the girder height, etc. Furthermore, the lag screw bolts with internal threads at both ends that engage with this bolt are selected according to the specifications of the bolt's threaded portion. In addition, to assist in maintaining the load-bearing capacity of the joint between the through-column and the girder during an earthquake, a shear shaft (pipe) is installed on the girder side beforehand. After the girder is in contact with the through-column, a drift pin is driven into the column to fix the column and girder. Then, the double-threaded bolt with a small hexagonal head on one end and the internal female threads of the lag screw bolts with internal threads at both ends are engaged and tightly fastened, and secured with a hexagonal nut. This allows for efficient and quick work, improving safety during work at heights and maintaining the load-bearing capacity of the building structure over the long term.

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