Study On The Economic Transformation Mode Of State Owned Forest Region In Heilongjiang Province

Glulam which is the main material of the modern timber structure has the decentralized imperfection, high strength, free section size and member shape and reasonable load. However, there are some defects in the glulam when glulam timber beams are bent, such as compressive strength incompletely used, insufficient tensile strength of beam bottom glulam and brittle failure, and the like. Based on above situation, a new steel and wood composite member named steel plate strenghthened glue-lumber beam is proposed in this paper, by which the compression is borne by glulam, the tensile is borne by steel plate and the prestress can be applied during production process. This kind of glulam will make full use of the compressive strength of glulam and the tensile strength of steel plate, and then improve the bearing capacity of beams and decrease the beams section size. This thesis, therefore, is of great significance in academic value and social practice. The following research is made in this paper.For steel plate strenghthened glue-lumber beams, a set of assist device was developed, which had two founctions:the first was it can pressure transversely on the steel plate strenghthened glue-lumber beams as well as precisely control the value of applying pressure to ensure a more uniform layer of paste so that steel and glulam beams can work together to improve their carrying capacity; the second was it can apply prestress to ordinary steel plate strenghthened glue-lumber beams and the external prestressing tendons did not destroy the beam section as well as the small space required for the construction so that the prestress would be more conveniently and easily applied to glulam and the deflection would be effectively controlled, making full use of high-strength steel plate.Through the bending tests of thirteen batches(in all:39) beams, the influence of plate thickness, paste position of steel plate and additional screw or not on bending performance of ordinary steel plate strenghthened glue-lumber beams was researched. Compared with ordinary glulam beams, when the 2mm,3 mm and 4mm thick steel plates were affixed, the bearing capacity was increased 30.28%,56.91% and 32.05% respectively, and with the increase of steel plate thickness, the bearing capacity was increased first and then dicreased. Compared with ordinary glulam beams, when the same thick steel plates were affixed and screws were set, the bearing capacity was increased 41.60%,57.53% and 59.04% respectively. With the increase of steel plate thickness, the bearing capacity was increased; compared with the same thickness steel plate strenghthened glue-lumber beams, the bearing capacity was increased 11.32%, 0.62% and 26.99% respectively, and reinforcement effect of screws was more obvious with thicker steel plates. Compared with ordinary glulam beams, when the 2mm,3mm and 4mm thick steel plates were affixed at the second layer bottom beams, the bearing capacity was industrial clusters, enhance the soft power of forest construction, to protect and improve people’s livelihood recommendations.