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LATERAL ANNALYSIS

Lateral Analysis is a term used by engineers to define the process which eventually lead to the design of walls for shear.

Shear may include strain, tension or stress in regard to the strength of the wall or structure in and of itself. The procedures can be tricky as far as tracing the full range of load divergence. Lateral loads may be affected by wind, seismic occurrence, occupants, water, etc. The resistance to lateral capacity is in part a function of the surface soil type and stability, and the effective projected area of the structure bearing against the soil. Whichever produces the highest lateral force, wind or seismic, will direct the proposed construction. Due to the light components of a wood structure compared to say concrete or wind load usually governs the building design. Utilization of new, and more advanced, analysis methods permits a comprehensive assessment of the actual failure properties and ultimate strengths of structural systems.

Research continues on expanding the potential of advanced study, by expanding procedures that examine the effects of lateral buckling. Models have been developed utilizing modern analysis programs for a range of simple support beams and rigid frames to fully understand their lateral torsional buckling aspects. Studies have been made to examine the deviation of these structures under lateral buckling influences. It was found that the behaviour of simple beams and supports in solid frame structures is significantly different. In actual frame homes, the specific associations are a strong factor in terms of decisive frame capacities.

The new methods used are based on the observations from the studies of both simple support beams and rigid framework. The results are taken into account examining a flexible constraint factor in the strength, based on support capacities. For fixed frame structures, the new method is generally more conventional than the conditioned models. Now, the efficiency relies on the designer’s knowledge of beam member limitations. The design proficiencies now are more superior to those in the original design methods, especially for building frames with less rigid supports.

Advanced analysis is now closer to being utilized for general structural design. Modern changes in technologies and design, challenges engineers to not only reinvent the structural process, but to challenge the conventional ways of solving these complex architectural issues.

"A simple method to obtain the load distribution on the resisting elements of symmetric and eccentric setback structures subjected to lateral loading is presented. The compatible load concept is employed by the proposed method to subdivide the loading into load components, both translational and torsional. The proportional stiffness rule of force distribution can then be applied to each load component. In addition to being a practical design tool, the proposed procedure also provides an understanding of the load transfer mechanism involved in setback structures, especially in the region where the setback occurs and complication in behavior is expected."
Source: http://ascelibrary.org/sto/resource/1/jsendh/v113/i2/p209_s1?isAuthorized=no

"A method of successive approximations is developed for the lateral load analysis of multi-storey structures whereby the axial deformations are taken into account. At each step of the successive approximations lateral loads are first distributed among vertical structural elements. The solution of the system is then performed by analysing the vertical structural elements as independent substructures subjected to the distributed loads. By introducing the concept of substructuring, it becomes possible to handle the vast number of unknowns in groups of very small numbers. The effect of axial deformations can be taken into account indirectly, without increasing the number of unknowns. The relevant equations take quite simple forms, which reduces the solution time remarkably."
Source: http://www.sciencedirect.com/science/article/pii/004579499090235T

" The earliest provisions for seismic resistance were the requirement to design for a lateral force equal to a proportion of the building weight (applied at each floor level). This approach was adopted in the appendix of the 1927 Uniform Building Code (UBC), which was used on the west coast of the USA. It later became clear that the dynamic properties of the structure affected the loads generated during an earthquake. In the Los Angeles County Building Code of 1943 a provision to vary the load based on the number of floor levels was adopted (based on research carried out at Caltech in collaboration with Stanford University and the U.S. Coast and Geodetic Survey, which started in 1937). The concept of "response spectra" was developed in the 1930s, but it wasn't until 1952 that a joint committee of the San Francisco Section of the ASCE and the Structural Engineers Association of Northern California (SEAONC) proposed using the building period (the inverse of the frequency) to determine lateral forces."
Source: http://en.wikipedia.org/wiki/Seismic_analysis