FINITE ELEMENT: ANALYSIS AND DESIGN OF LINTELS

Abstract

An attempt has been made in this thesis to analyse, on a rtionl basis, the exact nature of the arch action existing over an opening in a masonary work. Thr- myth of the arching action has been explored and the design loads for the various locations and superimposed loading conditions have been investigated. The validity of considering a load triangle to be tho most probable loading case has been thoroughly exari.tnod, starting with a centrally located door opening 1.5 m wide and 2.0 m high, in a 8 m wall and u3irg the "finite Element" method of analysis the resulting stress 'atterns and the structural actions were studied. The variable whose effect wao studied was the higbt of the masonry over the lintel, In all four cases ware studied with different hihts of masonary over the opening with the help of a non dimensiunal ratio beinç the ratio of half the cle,r -pan ci the lintel to the depth of the mso1,ary abuve it. Each case in turn was exinod for four loedirc. cae i. o, gravity locds only cunccntrated loads it mid span, eccentric concentrated loads cnd a uniformly di ctrj butun lm d. (in xarniLetjon of tte reu Its obtii4od it will be seen that the height of thr masonary has a definite influenco on the resulting structural actions. The greater the height of the maonary axo to opening, the greater is the dispersion of load in the adjoining rnasonery. The distribution of principal streoses above the opening indicates that it is improper to conicicr the action as a arching action ard a "tied-arch" reprcentation woUld be more appropriate, on the basis of the principal stress distribution if truss model Is analysc'd for the superiosc6 'loads it will be seen that though the bonciinç, moments are negiectc1 P. reasonable estimate of the maximum tensile stress, to which the lintolmay b. subjected, is obtained, The reolts of analysis also indicate the setting up of a "tension block" at the ends of the wall which could initiai.c crcckin at thu ends. This effect it provided for coi:ld rninise the chanccu of failure initiated at the tcnsicn block. coking back in retrospect it will ba seen that the CQnVcntioflal de,-49n uethod tend th be, oversio, The additional safety being a direct result of the load disersion into the tdjoining maorry. Therccnmeudation of the Building Reseach ztation (u.x.) secnk to be more appropriate in canparisiox to the others since the reccrwended moment coeffic,tent3 are mct e realistic.