Phân tích dao động tự do của thanh có xét đến biến dạng trượt ngang bằng phương pháp phần tử hữu hạn

Tóm tắt

ABSTRACT:

The beam structure with a large cross-sectional height compared to the beam span, h/l1/5 (high beam) has been studied and widely applied in the fields of industrial, civil construction, traffic and irrigation. ..especially for high-rise buildings using vertical combined structural solutions (the lower floors are for showrooms, shops... need large space, while the upper floors are for hotels and houses ... only need small and medium space), in which people often use the structure of transfer floor, transfer truss or transfer beam with large cross-sectional height to transmit the load from the structure above to the foundation, because their ability to span large spans, they increase space, reduce the number of columns
and create architecture for the building, meeting the practical needs of people. The Euler - Bernoulli beam theory is commonly used today, ignoring the effect of lateral shear strain caused by shear force, this is only true for beams with a small cross-sectional height compared to the beam length (h/L<1/ 5), but for high beams, the Euler-Bernoulli beam theory is no longer true. Therefore, in this paper, the author uses the forced displacement method combined with the finite element method to study the free vibration of the bar with different boundary conditions with considering the influence of the shear strain, the theory used here is the full beam theory [5]. The research results show that the influence of the lateral shear strain on the natural frequency of the bar is very large, for example, for the bar with one end fixed and the other pinned , the
effect of the lateral shear strain is reduced by 34,075%, 38.707% compared to when the effect of lateral shear strain is not taken into
account.

Keywords: finite element; oscillate; vibration; oscillation...Phần tử hữu hạn, dao động...