1. TILT-UP CONSTRUCTION
GUEST SPEAKER:
KAREN S. HAND, P.E.

2. Introduction Karen S. Hand, P.E. BSCE – University of Missouri-Rolla
May 1993
Needham & Associates, Inc.
Consulting Engineers
May 1998-Present
TCA - Charter Member
2004 Achievement Award Winner for Innovation

3. Topics Panelizing the Building Connections
Architectural Considerations

4. Project Procurement
Clients can be Architect, Engineer of Record, Subcontractor, General Contractor
Design Build Specialty Engineer
Engineer of Record with Additional Scope
How do we as a specialty Engineer get the job? Clients are from different Avenues
Typically we are the Specialty Engineer: Coordination can be tricky since the rest of the structural design and architectural design may already be done. Inevitably there are changes.
Best case scenerio is to design the entire structure. Gear toward educating marketplace about the importance of coordination up front. Too often the tilt-up is thought of as a facade and not a structural system.

5. Tackling the Project PLANNING!!!!!! With the Architect
With the Engineer of Record
With the Contractor
Once we are awarded a project, how do we tackle the job?
Planning with the Architect, Planning with the Engineer, Planning with the Contractor

6. Preliminary Design
Know what your constraints are..Not the typical “design” issues…Think beyond the paper…know what assumptions have been made in the proposal by the contractor.
Limited Site
Crane Size
Weather
Preliminary Design for Tilt Up is different from any other type of design. There are more issues or constraints to consider than the typical steel frame design. A limited site can restrict panel size. May need to do stack casting where the panel sizes should remain constant. May need casting areas somewhere away from the building slab, effecting the crane capacity for reach. Crane size can effect the entire design. An experienced tilt up engineer can tackle these issues.

7. Planning Decide the approach Are there any unique issues to consider?
New Millennium used tented stack cast panels to keep an efficient heated area
EPA had 16” and 32” thick panels…discussed 3 different options to determine feasibility before making a decision on how to proceed.

8. Panelizing the Building
One of the most important steps in Design
What is panelizing?
Determining how the walls are divided into panels, what their shapes are and where the joints between them occur

9. Panelizing the Building
Coordinate with Architect and Steel Framing Engineer and Contractor
Goal for Panel Sizes:
Maximum Panel Size
Minimize Panel Joints

10. Panelizing the Building
Factors to Consider
Crane Capacity and Reach
Steel Framing Layout and Bearing Locations – Typical Embedment Pattern
Opening Locations – Adequate Jambs, Lintel Panels, Vertically Stack Openings
Locate Girders at Center of Panel or at Joint
Footing Step Locations

11. Panelizing the Building
Takes the same time to lift and set a large panel as a small panel. Take Advantage.
Efficient Panel Layout Effects the Cost of the entire project and should be considered one of the most important issues to coordinate.
Cost in Formwork
Cost in Embeds/Connections

12. Planning the Connections
Base Connections
Corner Connections
Roof Framing Connections
Miscellaneous Connections

13. Types of Connections Welded Embedded Metal Embedded Inserts
Most Common
Embedded Inserts
Allows for Bolted Connection
Eliminates Field Welding
Accuracy in Locating
Drilled In Anchors
Post installed
Cast-In-Place Concrete
At Slabs

14. Base Connections What type of foundation system is being used?
Continuous Footing
Reinforced Top and Bottom layer
Centered Under Panel
Spread Footing
Panel Spans Corner to Corner
Allow for Expansion and Contraction
Pad Footings used to be the standard.
Continuous Footings are now the starndard.
Shrinkage of the panels between the bearing pads after the panels are set can cause diagonal shrinkage cracks in the lower corners of the panels. Set shim packs or grout pads

15. Base Connections
Diagonal Shrinkage cracks in the corners due to restraint of bearing pads
Grout under the panels as soon as possible
Shim Packs or Grout Pads should be located ¼ from the end of the panel

16. Base Connections Friction – Old Days Pourback Strips and Slab Dowels
Embedded Plates or Angles
To Slab Option
To Footing Option
Free Standing Walls
Spandrel/Grade Beam Type
By eliminating the panel to slab dowels, the floor slab can be cast all the way to the inside face of where the tilt up panel will be located. This also eliminates the backfilling and slab infill operations required around the panel braces to fill the closure strip.

17. Pourback Strips and Slab Dowels
Slab is poured short of the panel location with a “closure strip” of about 3’-0”.
Dowels are “wet set” into the panel at the correct elevation to meet the center of the floor slab.
Backfill and insert rebar between slab dowel and panel dowel.
Closure strip is poured to finish off the slab.

18. Pourback Strip At Dock Wall

19. Pourback Strips and Slab Dowels
Problems with the procedure
“Wet setting” the dowels is cumbersome
Accurate placement
Finishing
Variations of Detail
Backfilling becomes a safety concern
Braces are still attached
Access is a problem
Panel layout on the slab could present access challenges to get these wet set.
Epoxy the rebar to the panel and/or slab
Use threaded inserts (not always accurately placed)

20. Backfilling ACI 551 Section 4.10.2
Prior to backfilling, place a strip of felt over the joint between adjacent panels below grade and pack with plastic roof cement. This prevents dirt, mud or water from leaking through the joint in the panels

21. Embedded Base Connections
Allows for the slab to be poured to inside face of where tilt-up panel will go
Eliminates Backfilling on Inside of Bldg
Connections can me made immediately

22. Embedded Base Connections
To Slab
Angle Embedded in the Slab, Plate Embedded in the Panel - Welded
Consider Expansion/Contraction in Slab and Panel
To Footing
Angle Embedded at Base of Panel
Second Angle is welded to Embed and Bolted to Ftg
Consider Additional Unbraced Length for Panel Design
Consider Corrosion
Consider Expansion/Contraction
Adding concrete over the embeds do not protect them against corrosion!!!

23. Dock High Walls Connection at Slab and at Footing Slab Connection
Resists Lateral Load
Reduces Unbraced Length for Compression
Footing Connection
Resists Lateral Soil Pressure behind Panel
Advantage - Base Fixity for Panel Design
Base Fixity can become very important with the small column strips at dock doors.

24. Panel to Panel Connections
Are they needed?
Not typical for tilt up
Common in Precast
Larger Panels and Wider Panels

25. Panel to Panel Connections
Tie panels together for Overturning Forces
Re-entrant Corners with Drag Strut Forces
Laterally stabilize two adjacent panels
Use a Butterfly Connection
Expansion and Contraction
Do not restrain any more movement with the connection than structurally required.

26. Corner Connections Thermal Bowing
Caulked Joints can fail prematurely – Not a structural performance issue
Expansion and Contraction
Do not restrain any more movement with the connection than structurally required.
Why do we make corner connections?
What happens if we don’t make a corner connection?

27. Roof Framing Connections
Diaphragm – Chord Connections – Continuous Angle also acts as Deck Bearing Angle
Drag Strut Connections
Joist Bearing Connections
Embedded Plate and Bearing Angle
Joist Pocket
Girder Bearing Connections
Embedded Plate and Angle/Plate
Beam Pocket
Forming Issues with Pockets, Erection Issue with Pockets

28. Ledger Connection Diaphragm Chord – Shear Forces
Deck Bearing – Gravity Forces
Lateral Restraint – Tension Forces
Continuous Angle
Different Thermal Coefficient of Expansion
Rigid Connection for Shear at Center of Panel
Sliding Connection for Gravity and Tension Forces

29. Typical Ledger Connection

30. Typical Joist Connection

31. Typical Girder Connection

32. Other Connections Mezzanine Connections Spandrels
Smaller Joist Spacing
Resist Temptation to use a Continuous Angle Welded at each Joist
Spandrels

33. Expansion/Contraction
Did I mention Expansion/Contraction is the most important thing to remember when designing connections?
Expansion/Contraction is the most important thing to remember when designing connections.
Let the panels “breathe”

34. Design Panels
Once connections have been planned you can design the panels for the constraints you have provided.
Eccentric Loads due to Bearing Connections
Unbraced Length for Panel Buckling
Base Fixity

35. Reinforcing Schedules
Once Panels have been designed, you will indicate the required reinforcing on the structural drawings.

36. Reinforcing Design Note regarding Reinforcing:
ACI 318 Section allows bar spacing up to 18 inches.
Best practice is to use smaller bars not to exceed 15 inches o.c.
When using a double mat of steel, you could stagger the mats to reduce the effective spacing if stretching to 18” but this requires additional chairs to support the upper and lower mat independently. Check with Contractor for cost impact.

37. Engineering Documents
Need to Transmit, with completeness and clarity, the general and specific requirements for tilt up panels.
Key Plan
Locate panels and indicate designation
Elevations
Each panel uniquely numbered
Drawn from inside of building looking out
Panel Dimensions and connection detail references
Joint sizes

38. Engineering Documents
Connection Details
Anchor sizes required
Embed Plate sizes and stud spacing
Reinforcement Details
Typical rebar placement
Clear coverages
Special Tie Configurations
Pilaster reinforcement if required
Specifications
Shop Drawings – Panel Layout

39. Detailing the Panels
Biggest Source of Field Problems are results of inadequate checking and correlating between Architectural and Structural drawings.
Design Engineer typically isn’t too concerned about getting all the architectural features coordinated.
Elevations on the Structural Drawings and on the Panel Layout Drawings are drawn from the inside of the building looking outward.

40. Panel Layout Panel Identification Locate and Identify Embedded Items
Locate Openings
Location of any recesses or reveals with details
Locate Architectural Finishes
Pull all dimensions from upper left corner

42. Communication
Communication with the Architect is vital to the success of the project
Communication with the Engineer is vital to the success of the project
Communication with the Contractor is vital to the success of the project

43. Architectural Considerations
Accent Panels
Applied Treatment
Surface Treatment
Reveals (Rustication)
Protrusions

44. Reveals (Rustication)
Most basic Architectural influence

45. Architectural
Sandblasting
Exposed Aggregate
Painting
Applied

46. Surface Treatments
Formliners with Brick or CMU Pattern

47. Thinset Brick Installation

48. Architectural Features

49. Thinset Brick
Patterns with Thinset Brick

50. CMU Facade Chameleon Wall Placed in Sand Casting Bed
Concrete Poured over the CMU Face

51. Curved Panels
Target – Lee’s Summit

52. Protrusions Platforming
Form up the recesses to allow for panel surfaces to protude from the face

53. Architectural Accent Panels
2004 Award Winning Project

54. EPA Panel Forming
Forming required unusual techniques

55. EPA Panel Forming
Reveals on each side of the panel required innovation to achieve

56. EPA Panel Forming
Penetrations in the panel for ductwork

57. EPA Reinforcing
Forced Column and Beam Strips into the Panel to allow for Insulated Voids

58. EPA Panels
Lifting 32 inch thick panel weighing 186,000 pounds

61. Questions
If you have questions in the future please feel free to contact me!!!