# An Assessment of the Impact of Protective Lifeline Safety Systems on Formwork Systems
## 1 Introduction  
Formwork systems are widely used in construction to make concrete elements [1, 2]. The height of the formworks can often be several dozen meters above the ground, which requires the involvement of the employees to work at heights and the need to use fall protection systems [3]. The structure of the formwork panels is based on a concrete retaining plate and a steel frame with assembly holes for connecting individual elements to a whole. The presence of assembly holes in the steel frame allows them to be used for the movement of assembly personnel without the need to use additional external scaffolding. These works are performed during both the assembly of the formwork and the inspection of its assembly, as well as during its dismantling and while pouring concrete. This makes it necessary to ensure full access to system connectors by carpenters and installers [4], as well as to ensure their mobility and the ability to move relatively quickly and freely [5, 6] and high ergonomics of work to reduce energy expenditure [7, 8, 9, 10, 11, 12]. Horizontal lifeline systems and formwork hooks are perfect for this purpose [13]. Horizontal lifeline systems are based on a system of fixed points and a steel or textile rope stretched between them, to which the carpenter connects. Such systems are also used on roofs, allowing free movement on their surface, and in formwork systems they can be mounted on top of the system [14, 15]. Mounting points are most often rigid elements, which means that the entire fall energy istransferred directly to the structural elements and on the climber's side to the absorbers. Another solution are posts with a plastic joint, which undergo plastic deformation due to the force of falling. During deformation, the energy of the fall is absorbed, which is beneficial for the climber because the free fall time is extended and the fall is gently slowed [16; 17; 18]. However, there are no reports in the literature that report on the values of forces acting on the formwork, as well as the stresses occurring at the place of mounting the horizontal fall arrest systems.  
However, carpenters performing assembly and inspection work must have free access to each of the connections of the assembly system. It is possible to use a scaffolding platform and a passenger lift system, which are energy-intensive and cost-intensive, or move directly onto formwork.  
For moving purposes, it is possible to use hooks, which are a universal solution, but formwork systems often have limitations in their easy attachment and detachment. Hooks are equipment dedicated to moving around the formwork, as well as for working with it. They constitute a rigid attachment to the formwork structure, which means that all of the fall energy is transferred directly to the structure. Data from the literature also lack the actual impact of the hook on the structure of formwork elements [19]. Therefore, in this article, an attempt was made to indicate the key force-stress factors that occur during a fall in formwork assembly. To reflect real working conditions, the tests were carried out under field conditions using the Hunnebeck, Peri, Uhlma and Doka formwork system and a mannequin with a typical human body structure, mass distribution and joints. These tests were preceded by a series of tests under laboratory conditions using a steel weight and dynamic falls. Since the test results are similar for different types of formworks, for the purposes of this article, the description of the Hunnebeck formwork system and the Manto type was limited.