The aim of the work presented in this thesis is to produc~ a
direct method to design structures subject to deflection constraints
at the working loadso The work carried out can be divided
into four main partso In the first part, a direct design procedure
for plane steel frames subjected to sway limitations is proposed.
The stiffness equations are modified so that the sway in each
storey is equal to some specified values. The modified equations
are then solved by iteration to calculate the cross-sectional properties
of the columns as well as the other joint displacements.
The beam sections are selected initially and then altered in an
effort to reduce the total material cost of the frame. A linear
extrapolation technique is used to reduce this cost. In this
design, stability functions are used so that the effect of axial
loads in the members are taken into consideration. The final
reduced cost design is checked for strength requirements and the
members are altered accordingly.
In the second part, the design method is applied to the
design of reinforced concrete frames in which the sway in the
columns play an active part in the design criteria. The second
moment of area of each column is obtained by solving the modified
stiffness equations and then used to calculate the mlnlmum column
depth required. Again the frame has to be checked for all the
ultimate limit state load cases.
In the third part, the method is generalised to design pinjointed
space frames for deflection limi tatlions. In these the
member areas are calculated so that the deflection at a specified
joint is equal to its specified value.
In the final part, the Lagrange multiplier technique is
employed to obtain an optimum design for plane rigidly jointed
steel frames. The iteration technique is used here to solve the
modified stiffness equations as well as derivative equations
obtained in accordance to the requirements of the optimisation