Tag: Stress
Creep (Dimensional stability)
Creep is defined as the gradual increase in strain with time for a constant applied stress after accounting for other time-dependent deformations not associated with stress, namely, shrinkage or swelling and thermal strain. Hence, creep is reckoned from the elastic strain at loading, which depends upon the rate of application of stress (see Section 3.2)…
Stresses and deflections in service
A composite beam is usually designed first for ultimate limit states. Its behaviour in service must then be checked. For a simply-supported beam, the most critical serviceability limit state is usually excessive deflection, which can govern the design where unpropped construction us used. Floor structures subjected to dynamic loading (e.g. as in a gymnasium) are also susceptible to…
Effect of slip on stresses and deflections
Full-interaction and no-interaction elastic analyses are given in Section 2.2 for a composite beam made from two elements of equal size and stiffness. Its cross-section (Fig.2.2(b))can be considered as the transformed section for the steel and concrete beam in Fig .2.16 Partial-interaction analysis of this beam (Appendix A)illustrates well the effect of connector flexibility on…
Uplift Shear Connection
In the preceding examplem the stress normal to the interface AOB (Fig.2.2) was everywhere compressive and equal to w/2b except at the ends of the beam .The stress would have been tensile if the load w had been applied to the lower member. Such loading is unlikely, except when traveling cranes are suspended from the steelwork of a…
No shear connection
We assume first that there is no shear connection or friction on the interface AB. The upper beam cannot deflect more than the lower one, so each carries load w/2 per unit length as if it were an isolated beam of second moment of area bh3/12, and the vertical compressive stress across the interface is…
Bearing Stresses
These may occur in a wood structural member parallel to the grain (end bearing), perpendicular to the grain, or at an angle to the grain. Bearing Parallel to Grain The bearing stress parallel to grain Æ’g should be computed for the net bearing area. This stress may not exceed the design value for bearing parallel…
Air-Stabilized Structures
A true membrane is able to withstand tension but is completely unable to resist bending. Although it is highly efficient structurally, like a shell, a membrane must be much thinner than a shell and therefore can be made of a very lightweight material, such as fabric, with considerable reduction in dead load compared with other types of construction. Such…
Thin-Shell Structures
A structural membrane or shell is a curved surface structure. Usually, it is capable of transmitting loads in more than two directions to supports. It is highly efficient structurally when it is so shaped, proportioned, and supported that it transmits the loads without bending or twisting. A membrane or a shell is defined by its middle surface, halfway…
Stresses in Arches
An arch is a curved beam, the radius of curvature of which is very large relative to the depth of the section. It differs from a straight beam in that: (1) loads induce both bending and direct compressive stresses in an arch; (2) arch reactions have horizontal components even though loads are all vertical; and (3) deflections have horizontal…
Continuous Beams and Frames
Fixed-end beams, continuous beams, continuous trusses, and rigid frames are statically indeterminate. The equations of equilibrium are not sufficient for the deter mination of all the unknown forces and moments. Additional equations based on a knowledge of the deformation of the member are required. Hence, while the bending moments in a simply supported beam are determined only by the…
