TT-Type Slabs

TT-type floor slabs are used to bridge large spans and in the case of considerable loading. The underside of TT-type slabs is smooth. Nominal widths of TT-type slabs are 2400 mm and 3000 mm. On customer‘s request, slabs of lesser width can be manufactured as well, minimum width - 1500 mm. The ends of precast concrete elements can be notched to profile a rigid joint or reduce the overall height of the structure. An extra concrete layer ensures shearing force transfer to the adjacent elements and work of the horizontal diaphragm. The fire resistance of standard TT-type slabs is within 60-180 minutes. Anchor rods are concreted into the walls of slabs.

TT skerspjūviai

Fig. 1. TT-type slab standard profile

Technical Characteristics

Table 1 Characteristics of TT-2400 slabs

Profile	h mm	b mm	b₁ mm	b₂ mm	b₀ mm	Weight kg / m²
Fire resistance 60 min TT 2400 - 500 / 120 TT 2400 – 800 / 120	500 800	2390 2390	1120 1144	635 623	120 120	261 360
Fire resistance 90 min TT 2400 - 500 / 150 TT 2400 – 800 / 150	500 800	2390 2390	1150 1174	620 608	150 150	287 405
Fire resistance 120 min TT 2400 - 500 / 200 TT 2400 – 800 / 200	500 800	2390 2390	1200 1224	595 583	200 200	332 481
Fire resistance 180 min TT 2400 - 500 / 240 TT 2400 – 800 / 240	500 800	2390 2390	1260 1284	565 553	240 240	380 560

The curves of operating performance of precast concrete structures show change in TT-type slab load bearing capacity depending on opening length.

Fig. 2. Operating performance curves of TT -2400 slabs

Joints

To connect TT-type slabs, joints are necessary that are designed by Betonika UAB designers. The joints between TT-type slabs and supporting beams are installed using reinforcement of the upper levelling concrete layer or rods, attached to embedded parts.

Lateral joints with wall slabs or joints between adjacent TT-type slabs are obtained interlacing reinforcement mesh or welding to each other embedded parts, existing in the edges of slabs.

Drawing of joint assemblies you can find here.

TT-Type Slab Recesses and Holes

In the TT-type slabs, recesses can be profiled. In the edges, round openings can be made for process piping as well. Position and dimensions of recesses and openings must be identified in advance, because they reduce the load bearing capacity of a slab.

TT išėmos ir kiaurymės

Fig. 3. Recesses can be profiled in TT-type slabs

Table 2 Maximum width of recesses in TT-type slabs

l / b	TT - 2400	TT - 3000
Centre	1000 / 630	1000 / 930
Edge	1000 / 320	1000 / 460
Angular cut	1000 / 320	1000 / 460

Storage and Transport

The TT-type slabs are stored on semi-soft (e. g., wooden) battens, which are placed under the ends of the slab. When stacking slabs, the battens must be in one line above each other. In the same manner the slabs must be stacked during transportation. In the longitudinal edges of the slab, four lifting lugs are concreted. During hoisting, the angle between the straps must not exceed 90^o.