Academic literature on the topic 'Covered atrium masonry building'

The amount of construction waste (CW) at building sites is highly variable, for instance the CW generation index ranges between 50-300 dm3 per square meters of gross floor area. Today there is still a lack of knowledge about variables (building design, construction process, construction technologies, etc.) affecting the CW generation. The objective of this paper is to analyse the influence of multi-storey building design and some construction processes on the CW generation indexes. The CW generation was analysed for two groups of buildings with two different construction processes; one with plumbing and electric services installed inside the masonry element and the other with plumbing and electric services installed onto the masonry element and covered with water-resistant drywall system (reducing the construction waste generation). The gross floor area directly affects the amount of executed construction works in a building site. Since the most important works (concrete, masonry and cladding) for CW generation is related to gross floor area, gross floor of buildings is also directly related to CW generation. For buildings with gross area varying from 20,000 to 80,000 m2, there is a reduction of approximately 18% of construction waste only changing the plumbing and electric services installation system, from embedded in the masonry element to installed onto the masonry element and covered with water-resistant drywall system.

This paper deals with an actual problem of covered historic building atriums in Slovakia and their adaptation to the new function concerning building physics parameters. The aim of this contribution is to quantify the parameters of the new covered atriums regarding the sound parameters. The executed measurements in selected atriums were compared with the standard values (reverberation time, flutter echo) considering their new function (cultural, social, health).

Millions of non-engineered constructions in Indonesia are vulnerable to earthquake. Therefore, a simple, affordable and replicable method to strengthen the existing non-engineered construction in Indonesia is introduced. The retrofitting method described in this report is based on the principle of sandwich structures, having a masonry wall as core and covered on both sides with ferrocement layers. Numerical analysis result and shaking table test is included in this paper.

Caricin Grad, Justiniana Prima, urban planning, fortification, settlement, aerial photography, geophysical surveys, LiDAR, photogrammetry, excavations, GIS. Thanks to the application of modern non-destructive sensing and detection methods, in recent years a series of new data on urban planning in Caricin Grad was obtained. For the most part, the current research programme studies the Upper Town?s northern plateau, wooded until recently and hence the only previously unexplored unit of the city. In the course of this programme, the classical research method - the excavations started in 2009 - is for the first time combined with the systematic application of airborne and terrestrial sensing and detection techniques. The analysis of historic aerial photographs and topographic plans proved to be very useful as well. Along with them, LiDAR-derived DTMs, photogrammetric DEMs, different geophysical and orthophotographic plans are stored in the GIS database for Caricin Grad and the Leskovac Basin. In this way almost 80 percent of the plateau area was defined, and the obtained plan is hypothetical only to a small extent, which particularly refers to the unexcavated northern rampart of the Upper Town. Each source provided relevant information for the reconstruction of both the rampart and the settlement, which points to the value of a holistic approach to documentation from various dates. The first source to be studied were archival aerial photographs of Caricin Grad from 1938 and 1947 (Figs. 1, 2.1). The latter one was originally processed by Aleksandar Deroko and Svetozar Radojci}, who drew the plan of the town after it, labelling the unexplored Upper Town?s northern plateau as ?a probable habitation area?. The route of the northern rampart was aslo rather precisely determined by the authors (Fig. 2.2). Recently, these photographs were rectified and georeferenced in the GIS. The 1938 shot reveals the position of some towers as well, and it is also indicative of the way of construction of certain buildings. From the spatial layout of whitish zones, originating from mortar scattered along the slope, it can be deduced which buildings were constructed in opus mixtum - the horreum and the so-called Building with Pillars east of it. Traces of mortar can be observed along the route of the rampart too. These archival images are particularly important because they record the topography of the site before it was filled with heaps of earth from the excavations. The topographic mappings of this area were conducted in 1981 and 2006 (Fig. 3). The first plan was drawn after an airborne stereophotogrammetric survey of Caricin Grad, and in 2006, after the wood was cut down, this whole area was surveyed with the total station, with a density of nine points per square meter. This survey also resulted in a 3D terrain model (Fig. 3.2) indicating the layout of the buildings, which was to be proved by geophysical surveys and archaeological excavations. In the course of the Serbian-French reaearch programme, in 2007 geomagnetic surveys were carried out by Alain Kermorvan of the University of Tours. Thanks to the application of this method the remains of collapsed stone structures could be observed, and in 2015, in cooperation with the Roman-Germanic Central Museum, Mainz, and the Ludwig Boltzmann Institute from Vienna, the middle and eastern parts of the plateau were scanned with GPR (Fig. 4.2). Precise plans of the buildings were obtained in the areas in which LiDAR scanning and photogrammetric and geomagnetic surveys failed to produce clear images. Within the framework of the ArchaeoLandscapes Europe project, in 2011 we managed to organise an airborne LiDAR survey of the wider area of Caricin Grad. With its density of some 20 points per square meter, this scanning proved to be crucial for our comprehension of the town. The standard DTM provided numerous important data, especially its version calculated in the focal statistics function of the ArcGIS software package (Fig. 5. 1-2). These models show not only the route of the Upper Town?s northern rampart, the position of its towers and the layout of the buildings, but also the line of the Outer Town?s western rampart. Visible only in the DTM, this entirely new aspect of the Caricin Grad fortification has been attested by the excavations. Highly important plans of the town, and of the northern plateau of the Upper Town in particular, were obtained by UAV photogrammetric surveys. The first drone survey was conducted in 2014 within the scope of the same project. It resulted in a cloud with up to 1,600 points per square meter (Fig. 6.1-2). Unlike the LiDAR technology, photogrammetry cannot penetrate vegetation; therefore the preliminary clearing of the ground proved to be a most important step. After the 2015 campaign was finished, the excavation area in the Upper Town was documented again in the same manner. Regular photogrammetric surveys make possible the control of the works and reliable visual monitoring of the progress of exploration (Fig. 9). After the wood was cut down in 2006 and enormous heaps of earth from twentieth-century excavations and restoration works were carefully removed by machinery in 2008 and 2010, without disturbing the original layers of debris, wide excavations could begin. At first only the humus layer was removed from fifteen-meter squares, which was followed by technical drawing. In 2009 and 2010 we did not explore the debris or the cultural layers (Fig. 7.1-2). The additional two squares were opened and documented in the same fashion in 2011, when previously recorded buildings 11 and 15C were explored in detail, together with the part of the corridor between them where a bread oven was found. These buildings were oriented south-north, cascading along the mild slope towards the northern rampart of the Upper Town. Fragments of pithoi and carbonised fruits were found in the buildings, allowing for an economic interpretation. Judging by coinfinds, the buildings ended in fire after the year 602. Some of the buildings on the northern plateau were oriented differently, following the route of the northern rampart of the Acropolis in the east-west direction. In 2012 building 18 was excavated, leaning on the rampart. Rectangular in plan and some 12 by 7.5 meters large, it had a storey and a 7 by 5.5 meters spacious paved atrium in the west. Parallel to building 18 is building 20, the only one on the northern plateau constructed in opus mixtum. The two buildings are separated by a four-meter-wide street, running from east to west. This street, corridor 4, was partly cut in the rock. In some sections it had a substructure of fragmented debris. Building 20 has been carefully excavated for several years now. After the initial documenting, the surface layer of debris was removed, but not the collapsed structures with characteristic construction details; to the east of the building a collapsed wall was uncovered, containing as many as eight successive rows of stone and brick. Beneath these layers are the occupation ones, so far investigated only to a small extent. Building 20 is rectangular in plan, covering 25 by 12.5 meters. In its central axis there is a row of masonry pillars, dividing the building into two naves. On its western side there was a vestibule with a pair of doors matching the main entrances to the building. In the back of the vestibule, between these entrances and in axis with the pillars, there was a staircase. Adetailed analysis of these features led us to conclude that building 20 was a horreum, the first such edifice to be discovered in Caricin Grad. Taking into account the details of its ground plan, pillars, parts of collapsed walls and especially arches, it will be possible to reconstruct the original form of the horreum. Judging by the existing estimate, although somewhat rough, it was 13.5 meters high. It could be observed that in its later phases the horreum was partitioned into several rooms, and some of its entrances were walled up. In the vestibule only these later occupation phases were documented, as the original brick pavement was removed from its northern part. This was followed by a significant accumulation of cultural layers, which were sealed by the debris stratum. South of the horreum there is a spacious courtyard connected with the western street of the Upper Town. The Upper Town?s northern rampart has never been graphically reconstructed, despite the fact that Aleksandar Deroko and Svetozar Radojci} published its accurate (although schematic) ground plan as early as 1950 (Fig. 2.2). This part of the town has gradually been left out of the research focus, mainly due to the vegetation growth. Upon employing all the methods described above, however, it is possible to undertake such an effort. The ideal reconstruction suggested here includes the rampart route, the disposition and the form of the towers, and the possible locations of the posterns. The line of the rampart can be traced following the trenches left by the locals dismantling the walls. Only the section of the northwestern rampart in front of the western postern of the Acropolis cannot be presented, being still covered by massive earth deposits. On the other hand, the recently discovered western rampart of the Outer Town can be traced to its full length in the LiDAR-derived DTM. Its form can be easily reconstructed on the basis of the results of the 2012 excavations and the section of the same rampart uncovered east of the main fortifications in 1955-56 (Fig. 8). Having studied the microtopography of the terrain, we were able to determine the position of a number of towers. They were clearly indicated by bumps, regularly distributed along the northern and northeastern sections of the rampart. The position of the tower below the Acropolis? western postern could be easily determined as well, unlike the position of the tower opposite to the horseshoe-shaped one of the Acropolis fortification. Yet, it is hard to imagine that a hundred-meter-long section of the rampart was left unprotected. The rectangular shape of the towers is suggested because almost all the towers of the town?s outer fortification were constructed in that way. On the other hand, at present we cannot exclude the possibility that some towers were different, horseshoe-shaped in plan, like the ones on the Acropolis rampart. The disposition of the towers along the northeastern rampart of the Upper Town, in the area where the northern street presumably met the fortification, is not clear. This part of the site still lies under massive heaps of earth, and even the 1938 and 1947 aerial photographs are not indicative enough in this regard. However, the tower(s) might have been erected there, not only because the eighty-meter-long stretch of the rampart would be left without protection in an opposite scenario, but because it is likely that the northern street ended in a gate, or at least a postern. It is already known that some of the posterns on the Caric in Grad fortifications were defended by towers. The average distance between the towers of the town?s main fortification extends from 20 meters on the southern to 40 meters on the western rampart of the Lower Town; in our reconstruction the average interval on the Upper Town?s northern rampart is 44 meters. Another argument is that this gate might have connected the Upper and the Outer Towns. The position of the second postern is determined thanks to a depression in the terrain following the axis of another communication route in the Upper Town, leading from corridor 4 and running towards the north along the rows of buildings. Finally, the 3.8 meter width of the rampart in the section adjoining the northern tower of the Upper Town?s eastern gate may only indicate a staircase, the last reconstructed fortification element. On the plateau stretching between the northern ramparts of the Acropolis and the Upper Town fortifications a settlement developed with its radially distributed rows of buildings cascading down the slope. In the eastern part of the plateau there is the horreum, adjoined from the east by another building - the storage called Building with Pillars. Larger than the other buildings and constructed in opus mixtum, the two buildings follow the route of the Upper Town?s northern street, all of which indicates that they belong to the initial construction phase. One should not exclude the possibility that this part of the town was originally conceived as an economic district with storages and similar edifices. By all appearances, the original concept was soon abandoned. Already at the time of Justinian a settlement of numerous smaller buildings was created. With their walls of stone and wattle and daub, the buildings were roofed with tiles. Yet one should underscore that this construction phase, although less sophisticated than the first one, was accomplished according to a previously prepared plan; the spread of the buildings speaks to that effect. Shortly afterwards, if not at the same time, buildings were erected along the outer face of the Acropolis rampart - a clear indication of abandoning urban planning (Fig. 9). Public space was turned into private, in spite of the legal proscriptions of that time. During the last phase of the town?s life the buildings described, whether public or private, were partitioned into small rooms, often with fireplaces and with some of their entrances walled up. Just like the edifices constructed in opus mixtum, some of the more modest buildings from the second construction phase were used to store food - namely buildings 11 and 15C. The plan of this part of the site points to an organised settlement, most probably inhabited by persons servicing a significant clergy and administration. On the other hand, except for some houses - such as building 18 - small buildings along the Acropolis fortification, facing the main street, corridor 4, might have served as shops and workshops. Traces of furnaces, slag and bone working were also encountered in this area. The parallel application of classical research methods and modern techniques of sensing and detection enabled the reconstruction of the northern rampart and the urban matrix of the Upper Town?s northern plateau. Until recently among the least known parts of the town, this unit can now be regarded as one of the best defined. This is important not only for our understanding of Caricin Grad (Justiniana Prima), but also for the study of Early Byzantine urban planning in general.

Environmental heat stress on buildings through façades contributes to indoor overheating and thus increases demand for energy consumption. The study analyzed the problem, heat gain risk, of modern air-conditioned multi-level office buildings in tropics, for example Colombo. Plan form, orientation, sectional form and envelope were identified and theorized to understand design interventions to reduce the risk of getting heat stress on indoor environments. On-site thermal performance investigations in multi zones of identified three typical built forms, namely; shallow, deep and covered atrium plan forms, quantified the heat stress. Reaching the daytime indoor and surface temperature in peripheral zones of multi-story office buildings during air conditioning “off-mode” up to 38 °C–42 °C was seen as a critical heat stress situation to be addressed through building design. Shading or insulation on façades to control environmental heat gain and manipulation of building section for night ventilation to remove internal heat developed during the daytime are discussed. However, the significance of the plan form depth was found to be a main contributor in dealing with heat transfer to indoor space. Deep plan form was found to be more effective in controlling environmental heat transfer to indoor space across the plan depth.

The development of brickwork technique in ancient Kyyiv dates back to the X- th century. Old Rus` monuments’ masonry was made of large thin bricks called “plynfa” and lime-and-ceramic mortar. The size of the X-th – the XII-th brick sides varies from 27 to 36 cm, its thickness – from 2.5 to 4.5 cm. Different kinds of clay and loess extracted from the territory of Kyyiv and its vicinities were used as a raw material for brick and ceramic addition to mortar. That is why bricks in Kyyivan monuments differ in colour from light yellow to orange and dark red. Some gruss or cut straw were used as addition to fat clay. Limestone was brought to Kyyiv from Chernihiv area and lime mortar was produced in lime kilns situated near building sites. Ceramic addition to mortar called “tsemianka” was of refined clay, and crushed brick waste was used as well. Bricks were burnt under the temperature of 1000 – 1200 degrees C. That’s why bricks were very firm regardless of chink-like pores appeared as a result of hand-moulding of brick. The author took some investigation for the purpose to determine physical and mechanical properties of ancient bricks of Kyyivan monuments. Bricks were picked out of excavations or waste after building repairs. Small cubes were cut out of bricks with the height equal to brick thickness. Those samples were examined concerning their strength by compressing them perpendicularly to the sides the bricks were bedded in mortar. The strength of samples varied from 100 to 200-300 kg per sq.cm, water absorption was 10 % to 20 %. Some bricks taken from the Cathedral of the Assumption of Kyyiv-Pechersk monastery were the most firm. The strength of those samples was about 400-500 kg per sq. cm, their water absorption was the smallest, about 5.6 %. Because of high porosity and water absorption of building materials the surface of ancient masonry was exposed to destruction under the influence of temperature overfalls and precipitation, as it can be seen on the open parts of walls of the Old Rus` monuments. To prevent destruction of masonry, the walls of ancient monuments were covered with fine lime-and-ceramic mortar. Fragments of original plaster can be found on the walls of the XI-th century monuments St.Sophia Cathedral and St.Michael Church of Vydubychy monastery in Kyyiv. High level of well-developed building technique and high quality of building materials caused durability of ancient masonry and constructions in Kyyivan monuments, which preserved until nowadays.

The aim of the paper is to provide information on the defects in the construction of the elementary school in Vodňany. The building of the elementary school dates back to 1973. It is a reinforced concrete columns skeleton with a filling peripheral and internal dividing brick masonry. The object is used by the primary school and is permanently used and maintained. The extent of structural damage is stabilized in the current state and is not an immediate risk to the user of the object. It concerns only non-load-bearing structures (floor and partitions), the vertical load-bearing structures do not show a decrease and therefore the stability of the whole building is not compromised. However, actual damage complicates operation of elementary school and is very non-aesthetic. Concurrent damage to structures is the result of vertical deformation of the foundation soil. Vertical deformation of the foundation soil - sediment is the result of the building construction on a former creek which was not properly excavated and covered with a suitable backfill. Subsidence further strengthens imperfect drained rainwater from the roof of the building and leakage of rainwater drains.

The author investigates the building process of ancient Kyyivan monuments. After the wall foundations were laid, the erection of ground volumes of the edifice began. Wooden scaffoldings were arranged at both sides of a wall. The remains of caffolding preserved in the brick fabric can be seen on the front walls of the Transfiguration Church at Berestove and St. Michael’s Church of Vydubytsky monastery. The height between scaffolding tiers as well as the height of masonry between them varies from 1.3 to 2.2 m in Kyyivan monuments. The situation of red schist cornices in ancient churches is dependent on the abovementioned height of masonry tiers. The cornices are placed at springs of arches and vaults, at the level of the choir gallery floor, at the spring of supporting arches and basement of central dome. The location of cornices hence marked the completion of a certain building period. Being put over brickwork at the end of building period in autumn those cornices protected construction from precipitation during winter season. That is why cornices within the Kyyivan St.Sophia Cathedral have “throats” – grooves which are cut along the underside of cornices as a stringcourses to prevent water from running back across them towards the wall. One can easily determine building periods of the St. Sophia Cathedral according to the cornice levels in it. As far as building period at the times of Old Rus` took approximately six to seven months (from late spring to early autumn), the erection of the St. Sophia Cathedral with its five naves and double galleries was continued through five or six years. Cross-domed churches with three naves were built during approximately three or four years. For example St.Michael’s Church at Vydubytsky Monastery was built to the height of choir gallery during the first year, then to the height of vaults’ and domes’ springing during the second year, after that vaults and domes were completed during the third year. The types of vaults used in ancient Kyyivan architecture were barrel vaults, domes on pendantives and domes on high drums. Widely spread in Byzantine architecture groined vaults were not in use in the Old Rus` building until the middle of the XII century. Also there was a certain consecutive order in erection of parts of a church: at first its central cross-domed volume, then apses, narthex, galleries etc. were built. In a year or two after the edifice was built its walls were covered with plaster and decorated with murals. Building methods applied in the ancient Kyyivan monuments of the XI-th century formed the basis of Old Rus` architecture developed during the following centuries.

The external partitions of a building (walls, roof, etc.) in addition to their supporting functions must also ensure an internal microclimate suitable for comfortable human work, recreation and other activities. This article analyzes the thermal characteristics of the external walls of a residential house and thermographically examines the joints of the different structures of the building. Thermographical examination may be performed either passively or actively. In the former case, the object of the examination ir heated up to a given temperature, after which thermographical images of the object are taken and analyzed. In the latter case, thermographical analysis is made of the object in its naturally established thermal conditions. This article examines the thermal characteristics of the partition structures of a residential building. The values of the thermal properties of the materials are taken from the documentation provided by their manufacturers, and in their absence, the data of the technical building regulations is used. Calculated analytically: the wall of the western annex only meets the C energy class requirements, the insulation of the old part of the building raised the heat transfer coefficient of the partition to class A, the thermal characteristic of the eastern annex wall corresponds to the A + energy class. This thermographic examination showed that the facade covered by the fibrous cement siding absorbed less heat compared to the masonry facades. Based on theoretical calculations and the thermographic analysis, it is recommended to additionally insulate the western annex from the inside. If possible, it is also recommended to additionally insulate both facade joints with polyurethane foam and to seal them with waterproofing mastic to prevent the sunrays from reaching the foam.

An effective decrease of investments in additional insulation of buildings could be achieved by insulation from the inside by special building elements with high—thermal resistance. It is suggested by the authors to produce such elements from expanded polystyrene with additives decreasing combustibility. The insulating elements could be of two types: large expanded polystyrene boards (equal to the height of rooms) and 5.5 or 8.5 cm thickness and 18 or 25 kg/m3 density from one side covered by 2 mm layer of polymergypsum plaster and glass fibre with textured surface; insulating combined blocks of 25 cm width and 40–100 cm length and thickness of 7 or 10 cm, where expanded polystyrene board with thickness of 5.5 or 8.5 cm is covered by 0,75 layer of polymergypsum plaster. The description of such combined insulating elements construction is presented in the paper as well as the research data of physical-mechanical, thermal properties and test results on combustibility. The investigation data are summarised in 2 Tables and 7 Figures. As the conclusion, the recommendations for additional insulation blocks of flats from the inside by combined insulating boards and blocks are presented. Then the thermal resistance of external expanded clay concrete walls could be increased up to 2.0–2.1 m2 ·K/W, applying the insulating elements with thermal resistance of 1.3–1.4 m2·K/W and thermal resistance of ceramic brick masonry—up to 3.0–3.1 m2·K/W, applying insulating elements with thermal resistance of 2.0–2.1 m2·K/W. The test results on combustibility which the elements under discussion are recognised as material with low fire spread and could be applied as the insulation inside buildings, are presented. The results of economical calculations are presented too. It is pointed out that the proposed additional insulating blocks of flats from the inside by suggested insulating elements with high—thermal resistance is significantly cheaper in comparison with the well-known external insulation.

The new building of a university dormitory with workshops is the content of the presented thesis. The building consists of fifty-two beds for students’ accommodation with complete equipment in eight cells, three workshops and a technical support. This is a combination of reinforced concrete prefabricated skeleton and classical masonry building construction with insulation. The building has four floors. It is designed as seven towers with flat roofs, which protrude from a ground floor with a vegetative roof. Paved and parking areas are adjacent to the building. The project is designed into an urban area of Nový Jičín. Glass atrium and overall shape solution are the distinctive features of the proposal.

In November 1926 the excavators recorded moving lapilli from in front of this house and from the entrance but no finds were reported in these areas. On 8 July 1932 they recorded removing disturbed volcanic deposit from the middle levels in the northeast area of this insula. A breach (min. h.: 2 m), now patched, in the south end of the west wall of room 2 and 1.05 m above the floor, presumably penetrated into this space and documents disturbance after ad 79. Elia observed that the room had been covered and had been divided for all or part of its length by a ‘tramezzo ligneo’ which Ling interprets as a wooden partition to screen the stairway. In the north-east corner, are three masonry steps from a stairway which Ling argued ascended along the east wall. Ling argues that the installation of this stairway would have put out of commission the recess and lararium painting (dimensions: 0.55 m × 0.4 m) behind it. The remains of a late Third Style decoration are found on the walls. The loose finds from near the north entrance of this space and from near the entrance to room 3 were predominantly door-fittings, with the possible exception of a small marble base. A small key reported in the latter location may originally have been from storage furniture but was unlikely to have been in use as no other remains of such furnishings were recorded. The only other find in this area was a glass vessel of unknown type. Elia called this room an ‘atrium’. The finds are not particularly diagnostic but, even if this area was disturbed, they hint that it had been relatively unencumbered with furnishings, probably serving predominantly as a reception and access area for the rest of the house. The breach in the south end of the west wall of this room implies that it may have been disturbed after ad 79. The walls had a simple painted decoration but this room had no evident fixtures. According to Elia it was an ‘oecus’. The limited ceramic finds (a jug, a terra sigillata dish, and a lamp) are associated with lighting and probably with the serving or storage of foodstuffs.

<p>Conventional single family houses in Poland are being built in the improved traditional construction technology with massive load-bearing structure created by masonry walls made of ceramic , silicate or aerated concrete blocks, concrete foundations, concrete rib-and-slab floor and pitched timber or concrete flat roof. Expanded polystyrene and mineral wool are being used as thermal insulation. Such solution is very time- consuming and costly due to more and more expensive manpower. The change in economy from communism to free market caused the beginning of modern thinking about construction technology for family house to be light, eco-friendly, innovative and low-cost. The definition of the term “affordable” in relation to single family housing, as well as the socio-economical background for the low-cost housing in Poland is presented. The paper presents proposal of low-cost family house construction built in light steel frame technology. The supporting structure is composed of steel frame made of cold-formed galvanized C shape profiles. Externally the steel frame is covered with cement bonded particle boards, covered with polystyrene insulation and finishing coat according to ETICS system. From the inside the steel frame is covered with plasterboards. The main thermal insulation of the building is created by mineral wool filling the interior spaces of walls, ceiling and roof panels. Comparison of the total construction costs of a 136 sq m building made in light steel frame technology with buildings of identical dimensions made in other, popular and available traditional technologies showed that a steel technology is approx. 10-20 percent cheaper. The paper presents also the comparison of the low-cost model steel structure houses worked out in Czech Republic, Portugal, Romania and Brazil, including technical parameters, structure type and cost of erection.</p>