Eurocode Wind EN 1991-1-4:2005

Direction

Select the directions in which the wind forces are to be generated.

Building Height, h

Specify the building height directly or by selecting one of the calculated directions.

Building Width, b

Specify the building width as the maximum exposure dimensions or by specifying the width for wind in each direction.

Natural Frequency

For each direction, specify a natural frequency or use the program-calculated value.

Wind Force, Fw(z)

Setting	Description
Structural Factor (CsCd)	Type a value for the Structural Damping value, which is used in the calculation of the total logarithmic decrement of damping, δ, which is needed for the resonance response factor, R². You can select the following options for the structural factor: Use the calculated structural factor, Use the individually calculated components, size factor and dynamic factor, Type the size factor and dynamic factor to use in both X and Y directions.
Wind Pressure, We	Select to Use Calculated value for Peak Velocity Pressure, qp(z) or type a value to use. If you use the program calculated, you must supply the Air Density and select to use the calculated Turbulence Intensity, Iv(z) or specify a value. The calculated Turbulence Intensity also requires a specified value for the Turbulence Factor, K_I.
Pressure Coefficients, Cpe	Select to either Use Calculated values or type your own coefficients in both directions for both Windward and Leeward sides. Apply Correction for lack of windward and Leeward correlation — this option is per Section 7.2.2, Note (3). If used, the same rule applied to c_pe is followed to obtain d.

Basic Wind Velocity, Vb

Type the factors used to calculate the basic wind velocity, v_b.

Vb,0: Type the fundamental value of the basic wind velocity. National Annexes provide mapped values for v_b,0.
Direction Factor, c_dir: Type both X direction and Y direction factors.
Season Factor (c_season): Recommended value is 1
Probability Factor (c_prob): Recommended value is 1

Mean Wind Velocity, Vm(z)

Select the Terrain Category and select the Use Calculated option for the Roughness Factor, cr(z), or type a value to use.

Type a value to use for Orography Factor, co(z) or select the Use Calculated option and then specify the values as needed per Annex A.3.

Generate Additional Load Cases for Analysis with Tension-Only Members

RAM Frame utilizes a nonlinear analysis algorithm to keep track of tension-only members during solution of the structural model under applied loads. Since the process has a nonlinear (iterative) nature, analysis results can not be simply superposed with other results as in load combination option in RAM Frame. Therefore, each lateral load case (wind or seismic) are solved separately.

Since the direction of the lateral loads become important in an iterative analysis, RAM Frame provides an option such that additional load cases can be created upon user request. When Generate Additional Load Cases for Analysis with Tension-Only Members in generating lateral load cases (wind and seismic load cases only) is invoked, additional load cases are created. For instance, there are 12 load cases generated for a regular IBC 2000 (ASCE 7-98) Wind load case. If this box is checked, the number of the load cases becomes 22. Additional load cases are created to account for directional effects of applied loads so that the most severe loading case is captured.

RAM Structural System Help

Eurocode Wind EN 1991-1-4:2005

Conceptual example of additional load cases for tension-only members