MMK224757 - Tunnel Form vs. Flat Slab Systems: Construction Report

This report provides a detailed comparison of tunnel form and flat slab construction systems, evaluating their elements of implementation, construction methods, component compacts, strengths, and weaknesses. Tunnel form construction is presented as a method that casts walls and slabs in a single operation, ideal for repetitive structures like hotels and residential blocks, creating high-quality, load-bearing cellular structures. Flat panel systems, conversely, are described as monolithic concrete structures composed of columns and slabs, with drop panels enhancing shear resistance, suitable for linear designs. The report further discusses the construction methods for both systems, dimensional planning considerations, stability and structural performance, and acoustic, thermal, and fire-resisting capabilities, providing a comprehensive overview for informed decision-making in construction projects. This assignment was completed for the module MMK224757 - Construction Technology.

CONSTRUCTION TECHNOLOGY
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Introduction
Concrete structural systems have to be functional, constructible, cost effective as well as durable.
The system chosen has to be of adequate strength and in most case appealing in aesthetics terms.
The system must as well be of deflections which are within the acceptable standards and limits as
well as in seismic regions have to be of a capability of absorb the enormous quantities of energy
produced by seismic waves. Making a choice on a structural system may be at times a great
challenge and process (Celik, Sucuoğlu & Akyuz, 2015). Every concrete flat slabs construction
as well as tunnel form construction are by far and large concrete building systems but using a
comparison methodology of the two kinds of systems in the following aspects: elements of
implementation, construction method as well as components compacts, the weakness as well as
strengths of each of the systems can be attained and finally the appropriate place for the adoption
of each of the systems based on the results established (Pi et al., 2018).
Tunnel form construction systems
Tunnel form refers to a formwork system which enables the contractor to cast walls as well as
slabs in a single operation in an everyday cycle. It brings together quality, speed as well as
accuracy of offsite or factory production accompanied with the economy as well as flexibility of
construction of in-situ as well as acknowledged as a modern construction method (MMC). The
product in this process is a cellular reinforced structure having surfaces of very high quality and
only needs just but minima finishing to enable direct decoration (Mahbub, 2016). The end walls
of such structure as well as the facade as often easily finished using units that are thermally
insulated which may be clad as is needed.

Tunnel formwork constructions systems are composed of panels in either directions that are set
are perpendicular angles and are supported using prons and struts. The key elements in the
structure are the wall elements which serve as the primary elements for carrying loads as well as
the slabs that are almost of equally thickness as the walls. Buildings constructed using tunnel
formwork systems lack either columns or beams and the structure is often having a reduced
number of joints. Each of the half tunnel form is in the shape of an inverted L; with the portion
of the wall being typically between 2.4 to 3 m in height (Jasvi & Bera, 2015).
Every form is composed of wheels that are built in as well as a screw jack that is used for the
purposes of adjusting the form elevation. The two halves of the form are often locked together
through the use of a roof lock that as well as serve to maintain tolerances of flatness between the
two forms to about some thousandths millimeter. An adjustable or flexible diagonal support
which extends from the wall all the way to the deck form is one of the main pieces of hardware
on a tunnel form. The main role of this hardware is transferring to the wall the weight of the deck
and finally to the wall beneath the floor slab. These supports must be adjusted as well as
cambered prior to the commencement of a project to accommodate the weight of the concrete
laid on the deck (Nosenko, Domnitskiy & Shemshura, 2016).
Tunnel form construction system generates a structure that is efficient in load bearing that may
be applied in an avalanche of applications. It is specifically very effective in projects that are
often suited to repetitive structure construction key among them hotels, student accommodation,
residential blocks, prisons as well as barracks. The conventional technique would involve the
construction of floors and walls separately (Ciuperca, 2015). With the interaction of tunnel form
systems, locking together of storey height inverted units in the shapes of L is done to come up
with an inverted wall in a U-shape, ceiling and floor forms that are cast as one unit. The

doorways as wells as the corridors are accurate boxed out and the conduits installed to ensure
effective lighting and the reinforcement effectively fixed. This is then followed by casting of the
concrete.
More often than not, heaters are installed within the forms and the tunnel ends sealed. The
increased temperature plays a role in fastening the process of gaining of strength by the concrete
and it is possible to strip and reposition the forms the following day (Richard, 2017). The forms
are normally steel-faced and the resultant cast surfaces may be decorated using a minimum of
preparation. Even though the system is established to be most ideal to a regular pattern of
identical rooms, the changes in the breadths and height may be tolerated through the use of infill
panels.
Figure 1: Components of a tunnel form construction system

Precast Flat Panel System
A flat panel system is a section of the elevated panel systems that may be classified as either
beamless or beam supported. This concretes, which is cast on site is structurally monolithic
meaning that it exhibits continuity among the elements which in turn permit the flow of loads
throughout the structure (Hamid et l., 2018). This is achieved since the walls, columns as well as
the floors work all together as a single piece unit in transferring loads without the use of bolted,
pinned, welded or even grouted connections. A precast flat panel system is composed of a
structure of column and slab accompanied with drop panels as well as column capitals at the
connections of the slab and column. The drop panels mainly serve to offer greater shear
resistance at the regions of the columns. In cases where there is maximization of shear
structurally, the drop panel has to be extended to at least a sixth of the span of the slab in every
direction and its drop beneath the slab has to be not less than 25% of the thickness of the slab
(Lim, 2015).

Figure 2: Movement of Forces
Figure 3: Details of a precast flat panel system and minimum code requirement for drop panel
dimensions: (a) Typical precast flat panel system, (b) minimum drop panel dimensions, (c) Drop
panel depth based on dimension lumber (Mahbub, 2016)
Method of Construction
Flat-Slab System
The behavior of the frame is significantly influenced by the sequence of placement of the
concrete in the flat-slab system. In most cases, a waffle slab is often constructed as a beamless
slab. For the case of a beamless waffle slab, some domes on all the column sides are excluded in
order for the slab thickness at the columns to be similar to the depth of the joists. The thickening
of the slab at the columns offers the share resistance which prevents the slab from punching
through the columns (Pi et al., 2018). The slab formwork is composed of plastic domes that are
glass giber reinforced in nature and are placed on a form deck that is flat with the lips in such a
way that they are butting each other. The domes are able to tolerate repeated use just like the
pans and the dimensions of the domes have been standardized to generate 0.9m, 1.2m and 1.5m

distances of center to center between domes in different depths. These domes have a board
supporting lip on all the sider and are often laid on a platform deck.
Figure 4: A beamless waffle slab
Figure 5: A waffle slab standard dome sizes. (a) Three-dimensional view of fiberglass dome used
as a form for a waffle slab (b) Section through dome (Mahbub, 2016)
Tunnel form system
After the placement of the slab of the fist ground level slab, a 0.7 m high curb is cast by workers
at the position where a wall is to be placed. A reinforcement for the al passes through the top of
the curb, piercing into the floor. This is then followed by setting of the tunnel forms at heights of
0.05 m above the floor level against the curbs (Adler & Ellman, 2017). The next step involves
the attachment of steel blocks out to one of the form walls for the doorways, electrical,
mechanical as well as plumbing vertical classes (Hamid et al., 2018). The doors are often having

cam levers that are used in the collapsing of the bulkheads to facilitate their easy removal
thereafter. The tunnels are joined together using tampered ties that have both internal as well as
external spacers; with the spacing often being on 1.2*1.8m grids.
After positioning of the tunnel forms, the reinforcement for the above deck is placed followed by
rough electrical as well as block outs for plumbing which constitute the last and final step. In
some cases, the contractors place tarps over the end of the tunnel opening as well as supplying
heat to the closed systems in order to speed up gaining of strength in the concrete. In other cases,
the design strength of the concrete is increased so as to attain the 60% required design strength
for the removal of forms on the morning preceding the placement (Adler & Ellman, 2017).
The screw jack is lowered so that the wheels on the forms come into contact ith the floor during
the removal of the tunnel forms. This is followed by rolling out of each half of the tunnel through
exposing a lifting hole that is positioned in the form top often at about a third out its length. The
form is then lifted by a crane which places it to the subsequent location. Form oil is sprayed on
the sections of the wall as the form is being relocated out from the previous placement so as to
read them for the subsequent cycle (Ciuperca, 2015).

Figure 6: Tunnel building construction of a multi-storey and a prototype symmetrical storey plan.
Thick liners in the plan illustrate shear walls (Pi et al., 2018)
Dimensional Planning
Dimensional planning aids in bridging the gap that exists between the design of a product and the
production through offering the only dimensional quality management solution that capture the
results of the inspection of the real world and relating them to a complete associative life cycle
data model (Celik, Sucuoğlu and Akyuz, 2015). This enables an extension of the quality process
over the while enterprise and the supply chain allow designing and building anywhere with
enough confidence. Tunnel form construction systems are often curved in shape and in most case
best suited for the construction of non-linear forms of structures. This leaves this construction
form only viable for curved structures and those that would not adopt any linearity in their
structures. Precast flat panel systems are on the other hand linear in nature in involving the use of
panels in achieving the design and construction demands of structures. Panels are rigid for linear
structures only (Richard, 2017).
Stability and Structural Performance
The stability and structure performance of a structure sis determined as its ability to effectively
and successfully transfer loads from the super surface all the way to the subsurface. The stability
and structural performance is a factor of the available support system in a structure (Erwin et al.,
2018). A precast flat panel system is composed of a structure of column and slab accompanied
with drop panels as well as column capitals at the connections of the slab and column. The drop
panels mainly serve to offer greater shear resistance at the regions of the columns. The key
elements in the structure of a tunnel form construction system are the wall elements which serve

as the primary elements for carrying loads as well as the slabs that are almost of equally
thickness as the walls (Jasvi and Bera, 2015). Buildings constructed using tunnel formwork
systems lack either columns or beams and the structure is often having a reduced number of
joints.
Acoustic, thermal and fire resisting capabilities
The acoustic performance of a structure or building is influenced by the stability of the
construction materials used to resist or allow passage of sound and is normally a factor of the
thickness as well the nature of the material. Thermal and fire resistance are determined by the
thermal mass of the materials. Both the two modern methods of construction discussed in this
task are majorly composed of concrete (Nosenko, Domnitskiy and Shemshura, 2016). Concrete
has been known as one of the construction materials with excellent thermal mass. Thermal mass
defines the ability of a material to absorb and store energy. Changing the temperature of concrete
which is material of relatively very high density required a lot of heat energy. This renders the
material to be of an excellent feature in terms of fire resistance as it would take a lot of exposure
time to be affected by heat. The structures will thus enjoy good sound insulation by the walls as
well as the floors through the adopting of the inherent mass as well as the damping qualities that
are often associated with concrete. The thermal mass for precast flat panel systems serve to
flatten the differentials of the daily interior temperature hence reducing the energy demands of a
building. The more it is possible to flatten the interior temperature differential of a building, the
greater the amount of energy conserved (Lim, 2015).

External enclosure detailing options
Cladding options and costs of a building or a structure are determined by how deep the floors are
as well as the height of the structures and have been established to be able to account for up to
the tune of 25% of the total cost of construction of a building. Tunnel formwork construction is
often ideal for floors that do not extend to greater heights and tend to provide efficient cladding
platforms. The external enclosure for the two modern construction methods is concrete which is
often not costly with regard to cladding owing to the fine finish that is easy to handle. This
makes both methods of modern construction viable for cladding (Hamid et l., 2018).
Sustainability
The manufacture of precast flat panels is done insitu and then transported to the site where they
are assembled ready for use. Tunnel formwork is on the other hand made on site on which they
are to be used. In this regard, tunnel formwork reduce the carbon footprint on the environment by
reduction to complete elimination of the cost of transportation as well as the accompanied energy
in comparison with precast flat panels. Precast flat panels systems are easy to assemble and
disassemble and the process has minimal impact on the environment. This promotes
environmental sustainability as well as minimal disturbance to the natural ecosystem in the use
of the material (Sanders, 2014).
Logistics/ Cost
Many aspects are taken in consideration with regard to cost. It takes a very short while to
construct precast flat panels. Concrete panels have been established to result in marginally more
cost effective buildings as compared with tunnel from construction. Since the material used in
the foundations of the building is concrete which is a heavy material, structures done using

precast flat panel systems oaten tend to be slightly more expensive as compared with those dome
using steel as the case of tunnel form constructions (Schipper, 2015).
Conclusion
Of the two discussed methods of modern construction, it is recommended that the project Corner
Place aimed at the construction of 420 units for unit accommodation to adopt the precast flat
panel system in the construction. Owing to the nature of the structure that is to be erected,
precast flat panel system would be ideal in the achievement of the 15 floor of the building. Being
a student accommodation building, all the units will be similar in their layout and would just
involve either inverting a unit or reflecting another to attain the desired design. Still, with precast
flat panel system, the structural system of the building will be guaranteed as the building will be
having columns running from the ground floor level to the 15th floor level. This would ensure
structures performance as well as the stability of the building. Being a student accommodation, it
is anticipated that the students will be using the very rooms for personal studies which call that
material that has proper sound insulation properties, a property that is available with precast flat
panel system.

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