Compression members

Test pieces are specially prepared in the form of a disc or short cylinder, the compressive force being applied to the circular faces. The compression can be operated under two conditions either with perfect slippage between the rubber and the compressing members or with complete absence of slip. As perfect slippage is impossible... 

Column- A vertical structural compression member which supports loads. 

In theory there are two conditions under which a test piece can be compressed either with perfect slippage between the test piece and compressing members of the apparatus, or with complete absenee of slip. If there were perfect slippage, every element of the test piece... 

Cross braces, on the other hand, are tension and compression members. Cross braces can be pinned at the center or unpinned, and transfer their loads to the legs via wing plates or can be welded directly to the legs. 

Cross-bracing. Cross braces are tension and compression members. They may be pinned at the center or not. If the slenderness ratio of the cross brace exceeds 120, then the cross-bracing must be pinned at the center. 

Legs can be either cross-braced or sway-braced. Of the two bracing methods, sway-bracing is the more common. Sway-bracing is for tension-only members. Cross-bracing is used for tension and compression members. When used, cross-bracing is usually pinned at the center to reduce the. sizes of the members in compression. 

Note Evaluate all struts as tension and compression members regardless of sign, because when the vessel is sitting on the ground, the loads are the reverse of the signs shown. 

Columns with hinged ends they have perfect fireedom of motion at the ends in one plane, as in compression members in bridge trusses where loads are transmitted through endpins. 

A schematic diagram of the apparatus is shown in Fig. 1. The vertical dimensions in the figure are proportional but horizontally the apparatus is shown spaced apart with two legs, instead of the actual three, for clarity. The frame below the top plate, except the compression members, is made entirely of the alloy Ti-5 Al-2.5Sn. This titanium alloy is used for its higher yield strength and lower thermal... 

The design huckhng resistance Rb,Rb of the web of an 1, H or U section may be obtained by considering the weh as a virtual compression member with an effective breadth betf obtained from ... 

Particularly in skeletal structures, all compression members or elements should be provided with stiffeners and/or bracings to prevent local or general buckling before the design stresses are developed, unless such design stresses are reduced to take account of such local or general buckling. 

This section applies only to those compression members for which the load is applied coincident with the centroid of the member. If the load application is eccentric, then bending stresses as well as axial stresses occur. The effect of combined bending and axial compression is considered elsewhere. 

The effects of global (Euler) and local buckling dominate the design of compression members in any material. This is particularly so when designing FRP compression members. The inherent relatively low elastic modulus of FRP requires a full consideration of all possible modes of buckling. 

The rate of loading was approximately 0.1 kN/mmls in the most compressed member. 

The behaviour remained linear until a high value of the load was reached. Then the onset of bending of the most compressed member could be observed and the maximum load was obtained when this member buckled rather suddenly. After that the displacement could be increased under slowly decreasing load. Increasing rotations led some nodes to burst out and the truss to collapse. 

The ultimate axial force Ni in the most compressed member was determined from the strain measurements. The corresponding mean stress was far lower than the strength h, which indicated an elastic buckling phenomenon. Thus, the ultimate load N could be compared with the critical Euler s value, based on the buckling length I, which is related to the distance I between two successive nodes I, 0.78 I for the short trusses Ic 0-911 for the long truss. 

Failure of the truss is due to buckling of the more compressed member, in each storey the truss at a level of stress much lower than the strength. After the occurrence of buckling, the displacement can be increased under decreasing load, until some nodes burst out and the truss totally collapses. The behaviour can be considered as quasi-linearly elastic, with very little permanent deformation even after buckling has occurred. 

R. E. Ross and J. L. Bowling, NCI3 Concentrations and Decomposition by Dry Compression, Member Information Report 21, The Chlorine Institute, Washington, DC (1988), p. 101. 

In a lattice beam, flie top chord is a compression member and must be capable of supporting a column axial load without buckling. A T-type compression member is... 

When a compression member s cross-sectional dimensions are small in comparison with its length, the member is said to be slender. Whether a member can be considered slender is dependent on the magnitude of the member s slenderness ratio. The slenderness ratio of a compression member is defined as, KLJr, where K is the effective length factor for compression members is the unsupported length of compression member r radius of gyration = /M I the moment of inertia A the cross-sectional area. 

---