6. Tilt-Up Wall Panel Analysis - spWall Software

spWall is a program for the analysis and design of reinforced concrete shear walls, tilt-up walls, precast walls and Insulate Concrete Form (ICF) walls. It uses a graphical interface that enables the user to easily generate complex wall models. Graphical user interface is provided for:

• Wall geometry (including any number of openings and stiffeners)

• Material properties including cracking coefficients

• Wall loads (point, line, and area),

• Support conditions (including translational and rotational spring supports)

spWall uses the Finite Element Method for the structural modeling, analysis, and design of slender and non-slender reinforced concrete walls subject to static loading conditions. The wall is idealized as a mesh of rectangular plate elements and straight line stiffener elements. Walls of any geometry are idealized to conform to geometry with rectangular boundaries. Plate and stiffener properties can vary from one element to another but are assumed by the program to be uniform within each element.

Six degrees of freedom exist at each node: three translations and three rotations relating to the three Cartesian axes. An external load can exist in the direction of each of the degrees of freedom. Sufficient number of nodal degrees of freedom should be restrained in order to achieve stability of the model. The program assembles the global stiffness matrix and load vectors for the finite element model. Then, it solves the equilibrium equations to obtain deflections and rotations at each node. Finally, the program calculates the internal forces and internal moments in each element. At the user’s option, the program can perform second order analysis. In this case, the program takes into account the effect of in-plane forces on the out-of-plane deflection with any number of openings and stiffeners.

In spWall, the required flexural reinforcement is computed based on the selected design standard (ACI 318-14 is used in this example), and the user can specify one or two layers of wall reinforcement. In stiffeners and boundary elements, spWall calculates the required shear and torsion steel reinforcement. Wall concrete strength (in-plane and out-of-plane) is calculated for the applied loads and compared with the code permissible shear capacity.

For illustration and comparison purposes, the following figures provide a sample of the input modules and results obtained from an spWall model created for the reinforced concrete wall in this example. No in-plane forces were specified for this model.

In this example, ultimate load combination #1 is used in conjunction with one service load combination to report service and ultimate level displacements

Figure 3 - spWall Interface

Figure 4 - Assigning Dead Loads for Multi-Story Tilt-Up Wall Panel (spWall)

Figure 5 - Assigning Live Loads for Multi-Story Tilt-Up Wall Panel (spWall)

Figure 6 - Assigning Wind Loads for Multi-Story Tilt-Up Wall Panel (spWall)

Figure 7 - Assigning Roof Live Loads for Multi-Story Tilt-Up Wall Panel (spWall)

Figure 8 - Solve and Mesh Options (spWall)

Figure 9 - Multi-Story Tilt-Up Wall Panel Service Displacements (spWall)

Figure 10 - Multi-Story Tilt-Up Wall Panel Ultimate Displacements (spWall)

Figure 11 - Multi-Story Tilt-Up Wall Panel Axial Force Diagram (spWall)

Figure 12a - Out-of-plane Shear Force Diagram (spWall)

Figure 12b - In-plane Shear Force Diagram (spWall)

Figure 12c - Out-of-plane Shear Force Diagram (spWall)

Figure 13 - Multi-Story Tilt-Up Wall First Order Moment (M_ua) Diagram (spWall)

Figure 14 - Multi-Story Tilt-Up Wall Second Order Moment (M_u) Diagram (spWall)

Figure 15 - Ultimate Displacement at Critical Sections (First Order Analysis) (spWall)

Figure 16 - Multi-Story Tilt-Up Wall Panel Cross-Sectional Forces (First Order Analysis) (spWall)

Figure 17 - Ultimate Displacement at Critical Sections (Second Order Analysis) (spWall)

Figure 18 - Multi-Story Tilt-Up Wall Panel Cross-Sectional Forces (Second Order Analysis) (spWall)