Great, I will do a detailed research on the structural analysis of the Amasra Kemere Bridge, the materials used, its architectural features and its comparison with similar bridges in the world. I will also touch on the engineering studies that can be done to protect and develop this bridge. I will share the results with you as soon as possible.

Amasra Kemere Bridge: Structural Analysis, Materials and Restoration Works

(File:Amasra – panoramio (5).jpg – Wikimedia Commons) Amasra Kemere BridgeIt is a historical single arch stone bridge in the Amasra district of Bartın province, connecting Boztepe Island with the old Amasra settlement on the mainland (Kemere Bridge – Wikipedia). With its arched architecture Amasra CastleThe bridge, which connects the peninsula and island parts of the island, is approximately 5.9 m wide and 26.7 m long (Kemere Bridge – WikipediaAlthough the exact date of construction of the building cannot be determined, it is known that its foundations were laid in the Roman period and that it underwent repairs and additions during the Byzantine period in the 8th and 9th centuries. (Kemere Bridge – WikipediaThe bridge, which has been open to pedestrian and light vehicle traffic in recent years, has been strengthened with a comprehensive restoration since it was exposed to the waves and wind effects of the Black Sea.

Architectural and Structural Features

Kemere Bridge, single opening semicircular section It is an arch bridge. The arch piers sit on natural rocky ground on Boztepe Island and the mainland side and its span is approximately 26-27 meters. The bridge is built in the form of an arch from cut stone blocks; the stones are arranged in horizontal rows and most of them are from ancient structures. spolia is the material (Kemere Bridge – Bridging Byzantium).This is solid rubble and cut stone masonry The construction technique was preferred in ancient times due to the high compressive strength of the stones and their easy availability in the region (MASONRY ARCH BRIDGES AND ANALYSIS METHODS – HISTRUCTURAL – SAHCThe most important engineering feature of the arch form is that it transfers all the loads to the ground via stone blocks and supports (feet) by converting them into pressure. The keystone (peak point) of the arch and the other surrounding voussoir By placing the stones in the appropriate shape and angle, the structure is brought to a state where it can support itself. In the meantime, while the arch is being built, a wooden scaffold (rafter) must be installed at the bottom to provide support until the stones are completed (MASONRY ARCH BRIDGES AND ANALYSIS METHODS – HISTRUCTURAL – SAHCThe typical construction techniques of the period were used in the Amasra Kemere Bridge; it was built on solid rock-based piers. wooden formwork scaffolding The arch stones were laid with the help of. On the upper part of the bridge, there is a soil and rubble filled road layer covering the arch and stone railing (waterside print) walls on the sides. The deck width of approximately 6 meters shows that the bridge was strong enough to allow pedestrian and horse transportation of the period as well as light vehicle passage today.

In terms of materials, the bridge was built entirely with stone and mortar. The type of stones used is determined by sources. smooth cut limestone and there are also reused blocks taken from ancient building ruins (Kemere Bridge – Bridging Byzantium). It is estimated that traditional lime mortar was used in the joints between the stones. This type of construction allows the stones to work only under pressure and prevents tensile stresses, thus providing long-lasting durability. Indeed, when stone arch bridges are designed correctly, they can stand for hundreds of years within the limits of material durability. Amasra Kemere Bridge is such an engineering work that has stood for centuries. The architecture of the bridge is simple and functional; there are no decorative elements, the main emphasis is on the engineering design itself. In this respect, Cendere Bridge It has a similar engineering approach to the great arch bridges from the Roman period, such as: The Cendere (Septimius Severus) Bridge has a single span and a gigantic arch span of 34.2 m, and represents the peak reached by Roman engineering (Severan Bridge – Wikipedia). The Amasra Aqueduct, although smaller in scale, was built based on the same principles.

Comparison with Similar Historical Stone Bridges

Amasra Kemere Bridge shares architectural and engineering features with similar stone arch bridges built in different geographies throughout history. For example, Cendere Bridge (Adıyaman) is one of the largest single-arched stone bridges of the Roman period with a span of approximately 34 m and was built in the 2nd century (Severan Bridge – Wikipedia). Structures such as the Cendere Bridge were built with high-quality cut stones and precise engineering calculations to span large spans with a single arch, and have survived for centuries in a similar manner. On the other hand, the Mostar Bridge (Stari Most)It is an elegant stone arch bridge with a span of 30 m, completed in 1566 during the Ottoman period and was considered one of the widest arch span bridges in the world at the time it was built (Stari Most | History, Description, & Facts | Britannica). The Mostar Bridge consists of a single pointed arch leaning on the steep cliffs over the Neretva River, which gives its name to the city, and crosses the river without any central pier – similarly, the Kemere Bridge crosses the sea channel between Boztepe Island and the mainland with a single span. Both bridges reflect the aesthetic and engineering skills of the period in which they were built: the Mostar Bridge has been described as an engineering marvel with its elegant arch (Stari Most | History, Description, & Facts | Britannica), Kemere Bridge offers a similarly functional design, albeit on a smaller scale.

When historical stone bridges around the world are examined, it is seen that the arch form was preferred by the Romans, Byzantines and Ottomans for centuries. Large multi-arched bridges (for example, the Alcantara Bridge or in Anatolia Stone Bridge (Adana) ), single arch bridges provided a simple and durable solution when geographical conditions were suitable. Amasra Kemere Bridge is an example of this tradition in that it crosses the narrow strait with a single arch. In terms of construction technique and materials used, it is very similar to its peers in other parts of the world (Roman bridges, stone arches in medieval Europe, similar arch bridges in the Far East, etc.). In all of them, basic principle, is to cross an arch-shaped opening by taking advantage of the pressure-resistance power of natural stone and transfer the loads to the solid shores/foundations on the sides. Therefore, comparing the Kemere Bridge with other historical arch bridges from different periods and cultures reveals how universal an engineering solution the stone construction technique is in human history.

Construction Techniques in Historical Stone Bridges

A number of special techniques developed with the means of the period were applied in the construction of historical stone bridges. Arch bridge construction, first of all, it requires the construction of solid foundations and supports on both sides of the opening to be crossed. Ancient masters tried to establish the foundations on rocky ground as much as possible, even in difficult environments such as riverbeds or the sea, and when necessary, they dug foundation pits and created solid ground with rubble and mortar. The most critical stage in the construction of the arch is the creation of the arch form. For this wooden scaffolding and formwork It was used: A temporary wooden scaffold called the "center" was set up just below the arch, stone blocks (voussoir) were laid in a semicircular shape and raised on both sides, and finally at the top point keystone When all the stones were in place and the mortar was dry, the wooden scaffolding was removed and the arch became self-supporting (MASONRY ARCH BRIDGES AND ANALYSIS METHODS – HISTRUCTURAL – SAHCAt this stage, as the arch settles, there are small movements between the stones, the arch sags slightly and settles; thus, the load distribution becomes permanent.

Materials and workmanship techniques It is also very important in the construction of arch bridges. Stones are usually wedge-shaped (i.e. wide on top and tapering inward) It is carved in a form to fit the shape of the arch. This stone is called a "voussoir" and together with the keystone at the top, it forms the arch of the arch. Lime mortar is usually placed between the stones to ensure that they are interlocked and the gaps between them are filled. In some ancient bridges, dry (mortarless) stone laying techniques have also been seen; in this case, the stone surfaces are carved so precisely that there is almost no space between them. In the Roman period Pozzolan Strong mortars made of volcanic ash were also used, ensuring that the arches would last even under water.

After the arch is completed, a gently sloping embankment and road layer is constructed on top of the arch for the bridge deck. On both sides of the arch flooded (spandrel) walls The gap between the arch and the road is filled with material such as rubble and soil. This filling provides a flat road surface and helps the arch carry a more balanced load (will be explained in detail below). On the edges railing or parapet The purpose of the walls was to both hold the filling and provide security. The Amasra Kemere Bridge was also built with these traditional techniques: The side walls of the arch form a parapet integrated with the castle walls, and the filling material on the arch carries the originally stone-paved road surface.

Another method in the construction of historical stone bridges is the reuse of existing old building materials. For example, it has been documented that cut stone blocks taken from old buildings were used as reused materials in the construction of the Kemere Bridge (Kemere Bridge – Bridging Byzantium). In ancient times, when building a new bridge, it was common practice to use stones from nearby demolished buildings; this both saved material and shortened the construction time. However, the craftsmen preserved the integrity of the structure by adapting these reused stones to the size and shape of the arch. As a result, historical stone bridges workmanship, materials and design They were built with unique techniques and have survived to the present day by carrying enormous weights and resisting natural conditions.

Structural Behavior and Load Distribution

Behind the engineering success of an arch bridge lies the way the loads are distributed in the structure. Arch form, transfers the vertical loads (the weight of people and vehicles passing over the bridge and its own weight) to the supports by transferring them to the sides. For this reason, in arch bridges horizontal thrusts occurs; the arch piers must be strong enough to withstand the sideways thrust of the arch. In a well-designed arch, the resultant loads along the thrust line kemerin kesiti içinde kalır ve böylece taşlarda yalnızca basınç gerilmeleri meydana gelir. Taş malzeme basınca çok yüksek dayanım gösterirken, çekme gerilmesine dayanıksızdır; dolayısıyla itki hattının kemerin dışına çıkması, ilgili bölgede çekme gerilmesi oluşacağı için çatlak veya göçme riski doğurur. Bu prensip, 19. yüzyıldan itibaren “orta üçte birlik kuralı” gibi ifadelerle teorik temellere oturtulmuştur: itki hattı kemerin orta %33’lük kesiti içinde kaldığı sürece kesit boyunca basınç yayılır, dışına çıktığında çekme oluşmaya başlar ve yapı kararsız hale gelir (Thrust – Archie-M Knowledge Base).

An important factor affecting the load distribution in arch bridges is It is a filler. The soil/gravel fill and road layer on the arch takes point loads such as wheel loads and spreads them over a wide area. Thus, instead of a single wheel pressure on any point of the arch, the load is spread over a wider area. In fact, it is known in engineering applications that increasing the fill thickness on the arch increases the load that the bridge will carry. According to research, having at least a 30 cm fill layer on a stone arch is beneficial for load distribution; when the fill height is 60 cm and above, the distribution of live loads becomes much more effective (Improving a Stone Arch Bridge's Serviceability by Strengthening: Part 2 – Stone Arch BridgesThe thicker the padding, the tighter the arch distributed load arch bridges behave much safer under distributed loads than concentrated point loads (Improving a Stone Arch Bridge's Serviceability by Strengthening: Part 2 – Stone Arch BridgesTherefore, in the restoration of some historical bridges, additional filling or reinforced concrete layers were added to improve the load distribution (will be discussed in the reinforcement section below).

An arch bridge durability calculations, is made on the strength of the stone material and the geometry of the arch. Since the compressive strength of the stone is very high (for example, a good quality limestone can have a compressive strength of 50–100 MPa), it is generally critical to ensure that no tensile stress occurs in the arch. In the calculations, it is checked whether any tension occurs in any section of the arch, even in the most unfavourable load case. If the calculated thrust line lies outside the arch, it is predicted that there will be “hinging” at that point and that the arch may collapse with the formation of several such points. Engineers can also estimate the bearing capacity of arch bridges with simplified methods; for example, the MEXE method, gives an approximate carrying capacity using parameters such as the span, thickness, material condition and filling height of the arch. Nowadays, computer modeling of arch bridges is also done with the finite element method for more precise analysis (Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch BridgeIn this way, the behavior of stone bridges under both static loads and dynamic effects such as earthquakes can be examined, and if necessary, reinforcement projects are based on these analyses.

In the case of Amasra Kemere Bridge, due to the bridge's location open to sea waves dynamic wave loads is also an important factor. In the 2013 examinations, it was determined that the heavy storms had displaced the stones on the bridge piers and weakened the structure (Sewer pipe found on Roman bridge – Tourism News) (Sewer pipe found on Roman bridge – Tourism News). This required a comprehensive structural assessment that took into account not only the superstructure loads but also the environmental impacts. Experts documented the current condition of the bridge (survey), analyzed its historical structure (restitution) and prepared restoration/reinforcement projects with the data obtained (Sewer pipe found on Roman bridge – Tourism NewsThe calculations showed that the bridge was in danger of collapse if urgent intervention was not made, and support and repair work was started immediately.Sewer pipe found on Roman bridge – Tourism News). This case is an important example where the strength of a historical stone bridge was evaluated with modern analysis techniques and the necessary engineering measures were taken.

Protection and Strengthening Methods

Various engineering methods are currently being applied to preserve historical stone bridges and increase their carrying capacity. The basic principle in planning these methods is, without damaging the originality of the structure to increase its strength and extend its life. In cultural heritage works such as Kemere Bridge, first of all, regular maintenance and repair It is of great importance. Routine maintenance activities such as replacing stones that have fallen or come loose over time, filling gaps with appropriate mortar, taking drainage measures to prevent water from damaging the structure, and cleaning plant roots from the structure are the first steps to increasing the overall durability of the bridge (Improving a Stone Arch Bridge's Serviceability by Strengthening: Part 2 – Stone Arch Bridges). As with most historical buildings, protection with minimal intervention approach is essential; the minimum precautions required to keep the structure intact should be taken and intervention to the original structure should be kept to a minimum.

In today's engineering, there are several common methods to increase the carrying capacity of historical arch bridges. Strengthening technique stands out:

• Fill Raise or Expand: Increasing the height of the filler above the arch allows the wheel loads coming to the bridge to be spread over a wider area (Improving a Stone Arch Bridge's Serviceability by Strengthening: Part 2 – Stone Arch Bridges). Thickening the fill slightly raises the road level above the arch, but it is a simple and effective method, especially when it can be done without affecting the appearance of the bridge. Although the increase in fill creates an additional load on the arch, this load is fixed and distributed, so it does not significantly disrupt the general pressure condition of the arch; on the contrary, it reduces the effects of sudden and moving loads.
• Reinforced Concrete Saddle Addition: A thin layer is placed on the belt to be hidden under the padding. reinforced concrete layer (deck) is a very common solution in modern reinforcement. This steel reinforced concrete layer is poured to the shape of the arch and works with the arch, spreading the loads on the arch over a wide area. Research has shown that when a suitably designed reinforced concrete slab is added to a stone arch, the load carrying capacity of the bridge is experimentally up to three floors has been shown to increase (Improving a Stone Arch Bridge's Serviceability by Strengthening: Part 2 – Stone Arch Bridges). Nitekim Alman Demiryolları idaresi, geçmişte üzerine betonarme tabliye konulan kemer köprülerin hesaplanmaksızın %20 daha fazla yük taşıyabileceğini standart kabul olarak benimsemiştir (Improving a Stone Arch Bridge's Serviceability by Strengthening: Part 2 – Stone Arch Bridges). The reinforced concrete saddle method, when applied correctly, is invisible from the outside and does not affect the historical texture of the bridge; therefore, it can be a suitable solution for structures such as the Kemere Bridge. In fact, if necessary, the bridge's usable width can be increased by keeping the deck edges slightly wider (Improving a Stone Arch Bridge's Serviceability by Strengthening: Part 2 – Stone Arch Bridges).
• Fiber Reinforced Polymer (FRP) Reinforcement: Another technique developed in recent years is the application of carbon or glass fiber reinforced polymer (CFRP/GFRP) strips to the lower surface (concave part) of the arch. Since these lightweight composite materials have very high tensile strength, they form a "belt band" on the lower side of the arch and absorb the tensile stresses that may occur in the arch. This method, which can be applied from the lower surface without stopping traffic, increases the carrying capacity of the arch. a significant increase can provide (Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch BridgeFor example, it has been reported that CFRP strips applied to the lower surface of a historical arch bridge in Portugal significantly increased the load resistance of the arch (Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch BridgeHowever, the effect of FRP reinforcement on real-scale historical bridges may be somewhat more limited than on prototypes in laboratory experiments; because in real bridges, factors such as filling on the arch, mortar quality, and aging of the stones reduce the contribution of FRP relatively (Frontiers | Numerical Analysis of an FRP-Strengthened Masonry Arch BridgeHowever, the FRP method is an option that should be considered in works such as the Kemere Bridge, as it increases the carrying capacity by minimizing the visual impact.
• Stone Replacement and Repair Reinforcement: In some cases, it may be necessary to remove and re-wire damaged parts of the bridge. One of the methods applied in the 2013 restoration of the Kemere Bridge was to remove the stones forming the arch one by one by numbering them and to re-wire the arch with new and solid stones in accordance with the original after a solid foundation was created (Kemere Bridge – Wikipedia). This process can be seen as a "surgical" repair of the bridge. Of course, it is of critical importance that the stones and mortar used here are selected in accordance with the original material. Indeed, in previous years, the damaged parts of the bridge were repaired in the wrong interventions. concrete fillings It was understood that these were made, but they were not compatible with the historical texture. In the last restoration, it was explained that “the concretes that have no resemblance to the materials of the original work are being removed and replaced with materials that will restore its old appearance” (Kemere Bridge Restoration | Amasra.com.trThis shows that repairs that are incompatible with the original materials in historical buildings pose a risk to the structure over time and that the correct method is renovation with appropriate materials.
• Core and Foot Strengthening: Foundation erosion (scouring) poses a great danger, especially in bridges located in water. Since Kemere Bridge is also exposed to open sea waves, protective structures were added around the bridge piers in the 2013 reinforcement project. Wave-breaking quays By constructing the arch, both legs were surrounded by additional stone walls at a height of ~1.5 m above sea level to prevent the waves from hitting the arch directly (Sewer pipe found on Roman bridge – Tourism NewsIn addition, the underwater foundation filling was strengthened; the sea floor around the piers was covered with large rocks to prevent the waves from eroding the base (Sewer pipe found on Roman bridge – Tourism News). In this way, the bridge's legs were protected against horizontal wave loads and its stability was increased by allowing it to touch the ground in a wider area. As an unexpected situation during the restoration, the bridge's railing walls were hidden 30 cm in diameter One sewer pipe has been detected (Sewer pipe found on Roman bridge – Tourism News). The city's wastewater line was passed over the bridge years ago and hidden by covering it with concrete. Since this posed a risk of damaging the original structure of the bridge, the restoration team stated that the pipe should be removed from the bridge and taken under water (Sewer pipe found on Roman bridge – Tourism NewsCleaning up such modern interventions is also part of conservation efforts.

The above methods show the engineering approaches that can be applied to preserve and develop a historical structure such as the Amasra Kemere Bridge. Indeed, the work carried out by the Highways teams during the 2013–2014 restoration brought special solutions to life for this bridge: By installing a steel-supported carrier scaffold under the arch, the collapse of the structure was prevented (Sewer pipe found on Roman bridge – Tourism News), then the arch was dismantled and re-erected to ensure structural integrity, and external effects were minimized by adding piers and ground reinforcement around the piers. All these processes were carried out while remaining faithful to the original appearance of the bridge. At the end of the restoration, the bridge, preserving its historical texture It has been structurally strengthened and made capable of providing service for many years.

Scientific studies and engineering applications show that when the right techniques are used, historic stone bridges can be made durable enough to meet modern load conditions. For example, many arch bridges that have been standing for over a hundred years around the world still carry road and rail traffic; regularly evaluating their load capacities and strengthening them when necessary is critical for transportation infrastructure (MASONRY ARCH BRIDGES AND ANALYSIS METHODS – HISTRUCTURAL – SAHC). Amasra Kemere Bridge has become a work that will continue this tradition thanks to successful restoration and reinforcement applications. As a result, the preservation of a historical structure requires the harmonious application of material science and structural engineering. Correct understanding of the architecture and engineering of the bridge, comparison with similar bridges, and repair with appropriate materials and techniques have carried it into the future. In this way, Amasra Kemere Bridge continues its existence as both a monument that exhibits the engineering genius of past civilizations and a living historical bridge reinforced with modern engineering solutions.

Source: Technical information and restoration data regarding the bridge have been compiled based on relevant scientific publications, field reports and archive records. All data presented in this text are supported by reliable published sources on bridge engineering and restoration. Technical details and recommendations are based on findings in academic literature, and the source numbers indicated in the footnotes are provided at the end of the relevant explanations.

This article was prepared with the work of Kemal Onur Ozman.