# Innovative Suspension Structures: The Role of Straight Elements Under Asymmetric Loads
## 1 Introduction  
With the increasing demand for covering large building roof spans, various steel structures have been employed, including suspension structures, which have proven to be highly successful [1, 2]. In particular, this type of load-bearing structure allows for long spans, such as those seen on bridges [3, 4]. Due to their efficiency and excellent architectural esthetics, suspension structures have been widely used for medium- and long-span roofs for several decades [5, 6, 7, 8]. Given their relatively low structural mass, they are also classified as lightweight structures [9]. The efficiency of these structures lies in their ability to primarily withstand permanent and temporary loads through tensile (axial) forces [10, 11]. Suspension roof structures come in various shapes, ranging from parabolically contoured single-curvature plates to spatial (double-curvature) configurations [12, 13, 14]. Among thesuspension structures that can be used for both bridges and roofs, the two-span suspended structure with its upper chord designed as string deserves special mention, as this improves the working conditions of the deck [15]. The vast majority of these structures are designed using spiral ropes [16; 17], which require pretensioning to control and reduce displacements [1; 18]. However, these cables are susceptible to corrosion [19; 20]. The shape of a suspension roof is most commonly a parabolic shape, as this closely approximates the equilibrium shape of the load-bearing structures (cables) under a distributed symmetric load [6; 7; 21]. However, this design has drawbacks, particularly with regard to asymmetric temporary loads (e.g., snow and wind), which can cause significant kinematic displacements in suspension cables [22; 23]. Additionally, wind loads can induce considerable upward displacements in such structures [24]. It is also important to note that the modulus of elasticity of spiral ropes is lower than that of conventional structural steel, significantly increasing their deformability [17; 25]. To mitigate this issue, heavy docking panels are often used in conjunction with prestressing, which increases the axial forces of suspension structures and requires massive anchoring systems [1; 26]. To avoid such negative consequences, bending stiffness suspension load-bearing structures (\(E1\
eq 0\)) have been introduced in recent decades to stabilize the shape of suspension roofs [27; 28; 29]. These structures, also known as \"rigid cables\" or inverted arches, experience both tensile and bending stresses under load. Such \"rigid cables\" have also been proposed for suspension bridges [30; 31]. Such \"rigid cables\" are more sustainable compared with spiral cables. Their use enables the application of lightweight partition structures on roofs, reducing tensile forces in cables and consequently decreasing the mass of anchoring systems. A key advantage of \"rigid\" suspension structures is that they do not require pretensioning or complex anchoring connections. Their cross-sections are typically made from conventional rolled or welded steel profiles, simplifying both manufacturing and installation [32; 33]. Regarding these rigid suspension structure joints, we would like to note that the joints of the structure analyzed in this article are designed and manufactured in a similar way to the joints of conventional steel structures, using nodal plates and welding. Additionally, corrosion poses a lesser threat to these structures compared with traditional spiral ropes. However, \"rigid\" cables are still predominantly designed in a parabolic shape, similar to suspension roofs using spiral ropes [27; 28; 29]. This curvature presents challenges not only in operation, but also in manufacturing. In response, new suspension structures composed of straight elements with bending stiffness have been introduced for roofing applications [34; 35]. This allows the construction of flat roofs, which are advantageous from an operational standpoint.