THE WASHINGTON MONUMENT (1884) The purpose of this study is to show how this structure supports its own weight and wind load, by calculating its efficiency. 1 – Geometrical modelling 2 – Load modelling 3 – Internal forces 4 – Internal stresses 5 – Safety and efficiency

1 – GEOMETRICAL MODELLING2 – LOAD MODELLING unit weight of the stone : 23.6 kN/m 3 incorporated machinery : 58 kN /m (stairs + elevator) weight of the cap : 2670 kN 2.1 – Dead loads 2.2 – Live loads : wind The wind is assumed to act horizontally all along one side

Distribution of the critical wind speed along the height Wind pressure on the W.M. : ( Bernoulli’s flow law ) Calculations give a nearly constant wind force by unit of height : q = 32 kN/m Load modelling

3 – INTERNAL FORCES The maximal stresses are in the section x = 0

4 – INTERNAL STRESSES Cross-section at the base (x=0) 4.1 SHEAR STRESSES If we assume  max = 5  av, which is exagerated, we find a low value (105 kN/m2) compared with normal stresses (1790 kN/m2). Shear stresses can be neglected. 4.1 NORMAL STRESSES

5 – SAFETY AND EFFICIENCY safety factor = actual stresses or forces stresses or forces would induce failure 5.1 CRUSHING The maximum compressive stress that the stones used can support is kN/m TENSION The structure is made of stone blocks which can not resist tension stresses. Wind force which would cause failure : Wind speed which would cause failure :

5.3 - OVERTURNING Extreme winds could tip the W.M. over CONCLUSION The W.M is safe but not efficient regarding as well the dead loads than the wind forces. Maximum winds recorded in the region (60 m/s) have almost no influence on the dimension of the structure.