Engineering and design: Foundations subject to vibratory loads

BUREAU OF REClAMATION DENV RY 1111111 7/4 BASIC REPRINT WITH CHANGE 1 INCLUDED. 9 03741b /4~ • ll ~ Gf'l --- - · .. -- -- EM 1110·-345-310 a_ I ENGMC-ER 1/10 --:Jqt''=J/f). DEPARTMENT OF THE ARMY Office of the Chief of Engineers Washington, D. C. 20315 Manual No. 1110-345-310 19 May 1967 1qi7 e,_ l ENGINEERING AND DESIGN Foundations Subject to Vibratory Loads 1. Purpose and Scope. This manual provides interim engineering instructions for the design of foundations of structures subjected to vibratory or impulse loads, such as target-tracking radar antennas and space-vehicle launch facilities. This manual will be used by all elements of the Corps of Engineers responsible for the design of mili-tary structures. 2. Reference.s. a: TM 5-818-1 (EM 1110-345-147). b. Other references are listed in the bibliography and are re-ferred to by numerals in the text. · 3. General. Transient forces attendant upon rapid movement of large masses impose a requirement on foundation designers that is not present in the design of essentially statically loaded structures. Such forces can produce cumulative effects at frequencies near resonance, which can result in displacements larger than those which would be. created by static loads of the same force level. This phenomenon makes it neccessary that a designer be able to estimate the total amplitude of oscillation of the structure and foundation so that dis­placements will not be greater than those which can be tolerated when motion occurs at or riear resonant frequencies, the most critical con­dition. The analytical expressions and related information herein will permit designers to estimate the frequencies at.which foundations may be expected to resonate and the displacements of.the foundations which might be expected to result from applied forces at or near resonance. Three primary or fundamental mod.es of motion are treated: vertical EM 1110-345-310 1 <J May 1967 movement, rotation about a vertical axis (torsional), and rocking about a