1. 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

2. 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

3. 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

4. 3 – INTERNAL FORCES The maximal stresses are in the section x = 0

5. 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

6. 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 20000 kN/m 2 5.2 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 :

7. 5.3 - OVERTURNING Extreme winds could tip the W.M. over. 5.4 - 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.