AD-A250 778 DTIC S ELCTE MAY2 7 1992 C TILT-UP CONSTRUCTION BY RICHARD E. CROMPTON A REPORT PRESENTED TO THE GRADUATE COMMITTEE OF THE DEPARTMENT OF CIVIL ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING "DiSMhUT1ON STATUM- -A UNIVERSITY OF FLORIDA Appiovd for pu5kc relsoM; SPRING 1992 rMstribution UnPrnated9 TABLE OF CONTENTS LIST OF FIGURES.................. ......... .... .. .. . ... CHAPTER ONE - INTRODUCTION TO TILT-UP CONSTRUCTION..... .. ... 1 Definition of Tilt-up Construction....... . .. .. .. ... 1 Advantages of Tilt-up Construction....... . .. .. .. ... 1 History of Tilt-up Construction..............3 Typical Uses for Tilt-up Buildings.............3 CHAPTER TWO - PLANNING THE TILT-UP BUILDING ........... 5 When to Use Tilt-up Construction..............5 Will There be Enough Casting Space?............6 Other Considerations for Tilt-up..............10 CHAPTER THREE - THE FLOOR SLAB AND CASTING SURFACE.......12 The Concrete Floor Slab....................12 Cure Coats and Bondbreakers................12 CHAPTER FOUR - CONSTRUCTING THE TILT-UP PANELS.........16 Edge Forms.........................16 Reinforcement..................... 18 Sandwich Panels.....................18 Lifting Systems and Inserts................20 CHAPTER FIVE - ARCHITECTURAL TREATMENTS............25 Types of Architectural Treatments.............25 Exposed Aggregate Finishes.................25 Form Liners........................27 Rustication and Paint......................29 Stucco and Insert Decorative Rocks............30 CHAPTER SIX - RIGGING, LIFTING, AND PLACING TILT-UP ....... 33 Preplanning.........................33 Rigging for the Lift...................33 Making the Lift........................39 Plumbing Panels.....................41 Temporary Bracing.....................43 CHAPTER SEVEN - CONNECTIONS FOR TILT-UP CONSTRUCTION . . . . 48 Design Considerations....................48 Types of Connections....................49 Foundation Connections..................50 Panel to Panel Connections.................52 Roof and Floor Connections.................54 CONCLUSION...............................62 REFERENCES.............................63 BIBLIOGRAPHY.........................64 ii LIST OF FIGURES Figure 1: Panels Placed in Rows .......... ....... 7 Figure 2: Casting Slab for Building with Small Footprint 8 Figure 3: Typical Panel Layout ........... ....... 9 Figure 4: An Example of How to Form the Edge of a Panel 17 Figure 5: Sandwich Panels Have a Core of Insulation Surrounded by Concrete ..... .............. . 19 Figure 6: Ground Release Hardware Before Attaching to Panel ........ ...................... 22 Figure 7: Ground Release Hardware attached to panel . ... 22 Figure 8: Exposed Aggregate Finishes Can be Cast Two Ways . 26 Figure 9: Typical Form Liner ......... .......... ... 28 Figure 10: Rustication Used to Highlight Painted Areas . . . 30 Figure 11: An Example of a Panel using Trompe L'oeil . . . 32 Figure 12: Crane Rigged With 4 Rows Across and 2 Rows High 35 Figure 13: Crane Rigged With 4 Rows Across and 1 Row High 35 Figure 14: An Easy Way to Switch From a 3 Hi to a 2 Hi Rigging Configuration .......... __ ........... 37 Figur . 15: Changing From a 4 Hi to a 2 Hi Rigging Configuration .......... .......... . 38 Figure 16: Crane Performing a "Suicide Lift" or a "Blind Pick" . . . ._. ._. .. . .. . 40 Figure 17: Crane Operator Can See the Rigging When Panel Lifted This Way ...... ................. . 41 Figure 18: Plumbing Blocks Can be Used to Hold a Panel Upright. .... .. 43 Figure 19: Temporary Panel Bracing" . .. . .. . . . . . .. 45 Figure 20: Knee Bracing, Lateral Bracing, and End Bracing 46 Figure 21: Panel to Foundation Connection . ......... 51 Figure 22: Panel to Foundation Connection . ......... 52 Figure 23: Rigid and Nonrigid Connections .. ........ ... 53 Figure 24: Welded Panel-Panel Connections ... .......... . 54 Figure 25: Recessed Floor/Roof Connection .... ....... . 55 Figure 26: Angle Seat Used to Support Metal Joist ....... . 56 Figure 27: Wood Joist Supported on Wood Ledger . ....... . 57 Figure 28: Wood Beam Supported in Steel Shoe .. ........ . 58 Figure 29: Steel Beam on Pillaster .... ............. . 60 Figure 30: Double Tee on Concrete Ledger ... .......... 61 Ace~w. 1i4" For AvO1& 4l. oedes ,:D 1D3 t. i pec lal CHAPTER ONE INTRODUCTION TO TILT-UP CONSTRUCTION 1.1 Definition of Tilt-up Construction Tilt-up construction is a special form of precast concrete construction. The technique is used for constructing buildings by prefabricating concrete wall sections (panels) in a horizontal position on either the building's floor slab or on a temporary casting slab. Once the wall sections have cured, they are tilted to a vertical position using a mobile crane, they are temporarily braced in their final upright position, and finally, they are tied into the building's roof and floor system to become an integral part of the finished structure. Tilt-up is a fast, simple, and economical technique of construction which, in the past, has been used most commonly on one-story buildings. Today, however, buildings as high as six stories are being cast and tilted into position. 1.2 Advantages of Tilt-up Construction The economic advantage of tilt-up lies in its simplicity and speed of construction. Compared to other forms of precast concrete construction, tilt-up eliminates the need for expensive transportation of building components from the precast plant to the job-site. By casting panels at the project site, panels can be designed much larger than those that must be transported from a precast concrete plant. By 1 spending time up front in the planning stage of a project, the critical factors of constructing a tilt-up building are carefully considered to minimize total construction time. By applying skillful panel casting layout plans, the panel erection sequence can be accomplished very quickly in an assembly line type operation. Additionally, since the panel erection sequence can be set up to run quickly, the total time required for renting an expensive crane is minimized. Since the panels are cast horizontally at ground level, there is no expensive vertical formwork, and the formwork that is required is accomplished quickly and safely since the carpenters and steelworkers can work at ground level. Tilt-up buildings are inherently low maintenance since the concrete surfaces can be left unpainted and are not affected by moisture or weathering. Although the typical early generation tilt-up buildings tended to be simple and plain boxlike structures, today's tilt-up buildings have a limitless freedom of design for both shape and architectural treatments. In fact, it is difficult to tell that many recently constructed buildings are made by using the tilt-up technique. Tilt-up buildings can be very flexible since panels can be easily removed and relocated if future building expansions become necessary. Finally, tilt-up panels of 5-1/2 to 6 inches thick have the inherent fire safety rating of concrete buildings and "will provide a fire endurance of two hours or more" (1:3). 2 1.3 History of Tilt-up Construction The earliest recorded case of "job-site precasting began as early as 1906 when a railroad bridge, which had been precast [on site), was successfully set in place by a railroad crane" (2:5). Following the first successful use of the tilt- up technique, several small tilt-up structures were built over the next two decades by using tilting platforms or by using railroad cranes. Due to the high expense of laying railroad track for the heavy railroad crane or the expense of constructing the tilting platforms, tilt-up did not catch on as a practical technique until 1946. The significance of this date is simple: modern mobile cranes were developed during the period from 1941-1945 during World War II. After the war, tilt-up construction became a more popular construction technique since panel erection could be rapidly accomplished by the use of mobile cranes. 1.4 Typical Uses for Tilt-uR Buildings Tilt-up construction can be used for any type of low- to mid-rise building. The most common applications are found in warehouses. Warehouse buildings are typically 22 to 30 feet high, they are rectangular in shape, and they have a large floor area. These design aspects of warehouses readily lend themselves to tilt-up construction since the wall heights allow economical panel thicknesses, and the large floor areas provide plenty of room for casting the precast walls. By 3 using load-bearing tilt-up walls with a light roof system, the needs of a typical warehouse can be realized economically with tilt-up. Many of today's mid-rise office buildings are constructed using tilt-up. By applying the myriad architectural treatments available, designers can provide buildings that project the professional image desired by any company, and the building can be constructed quickly and economically. A few of tilt-up's most recent markets are in constructing shopping malls, mid-rise apartments, condominiums, townhouses, and hotels. 4 CHAPTER TWO PLANNING THE TILT-UP BUILDING 2.1 When to Use Tilt-up Construction The decision of which method of construction to use for a building is influenced by several factors. The most significant factor is the cost of the building. A building's owner typically will not be as concerned with his new building's construction method as he will be with the building's bottom-line cost. Tilt-up construction is not a technique that a contractor can arbitrarily decide to use on any reinforced concrete structure. The designer must specifically design the building from the very beginning with the intention of having it constructed using the tilt-up method. Since tilt-up panels typically experience stresses from three to four times higher during lifting than they do once they are placed into position, it is extremely important for the designer to consider the critical lifting loads during the design process. The overall cost of the building is going to be controlled by more than just the total material cost. For vertical concrete construction, a major portion of the total building cost can be spent in formwork and labor. If the owner and the designer decide concrete is the material of choice for a building, then tilt-up's potential savings for expensive formwork, labor, and time may become an attractive alternative. 5 2.2 Will There be Enough Casting Space? In addition to cost considerations, there are other site dependant considerations that must be weighed. A crowded job- site in an area like New York City would not readily lend itself to using tilt-up construction. The problems with a site that is bordered by other buildings and busy roads are the limited working room for the crane and the limited casting area. It is easy to visualize a building that is relatively tall with a small footprint, and a building with these dimensions in a crowded location cannot economically be constructed using tilt-up since the floor slab is too small to be used for casting the wall panels. Actually, there are two solutions for using tilt-up construction on a project where the building's floor slab is too small for casting wall panels that are tall enough to span from the ground to the roof. One solution is to construct smaller wall panels and then actually place panels on top of each other in their final position as shown in figure 1. The drawback of this system is the difficulty in safely bracing the panels during the construction. The second solution is to construct separate concrete casting slabs on the job site, and then use these slabs for constructing the building's wall panels. 6 Panels placed In double layer L -1A0 Door 4.,Opening Figure 1: Panels Placed in Rows To minimize the number of additional casting slabs required, the wall panels can be stack cast on top of each other which means that wall panels are actually poured on top of one another similarly to stacking a deck of playing cards on top of each other one card at a time as shown in figure 2. The major problems with using a separate casting slab are the additional expense required for constructing the additional casting slabs, and the panels are not cast near their final position which means more time and effort must be used to move the panels to their final position along the building's wall. 7