Mitmekordse hoone seinte ja postide koormusolukorra hinnang

Taimsaare, Allar (2020) Mitmekordse hoone seinte ja postide koormusolukorra hinnang. [thesis] [en] Assessment of the Load Situation of the Walls and Columns of a Multy-Storey Building.

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Abstract

Töös käsitletud hoone jäikusseintele mõjuvate tuulekoormustega tehtud arvutuste põhjal selgus, et seinte paiknemine omab suurt rolli mõjuvate jõudude osas. Hoone suhtes sümmeetriliselt paiknevate jäikusseinte korral vähendab seinte vahelise vahekauguse suurendamine oluliselt pöördumisest tekkivaid momente. Tehtud arvutuste põhjal selgus, et seinte paiknemine mõjutab oluliselt nende koormuseid ja sisejõudusid. Hoone suhtes sümmeetriliselt paiknevate jäikusseinte korral on oluline hoida seinte vahekaugus võimalikult suur. See vähendab ebasümmeetrilise koormuse ebasoodsat mõju. Seintes esinevad vertikaal- ja horisontaalkoormustest põhjustatud pikipinged. Ühes seina otsas summeeruvad survepinged, teises võib suure tuulemomendi ja ebapiisava vertikaalsurve korral tekkida tõmme. Kõigi valitud seinte korral jäävad ülemised kolm korrust täielikult surutuks ning tõmbepingeid seintes ei esine. Suurimad tõmbe- ja survepinged esinevad alumistel korrustel. Ülemistel korrustel pinged vähenevad. Konstruktsioonilahenduses on otstarbekas seda asjaolu arvestada ning kujundada seina paksus ja armeering vastavaks sisejõududele. Vundamentide mõõtmed on määratud lähtudes pinnase kandevõimest. Mõõtude määramisel eeldati vundamendi ülapinna kõrguseks 0,6 m põranda pinnast ja suurendati taldmiku paksust vastavalt vajadusele. Ühtlasi suurenes sel juhul ka rajamissügavus. Arvutustulemused näitasid seinte vahekauguse suurendamise ja sümmeetrilise asendi soodsat mõju. Kaks hoone ühes servas paiknevat seina vajavad töös käsitletud lähenemise korral nii massiivset vundamenti, et ilmselt õnnestuks leida ka otstarbekamaid lahendusi. Esimene eelistus on hoone jäikusskeemi muutmine – seinte paigutamine hoone suhtes sümmeetriliselt või uue jäikusseina lisamine hoone teise otsa. Büroohoone postide käsitsiarvutatud vertikaal- ja horisontaaljõudusid on võrreldud arvutusmudelist saadud tulemustega. Mudelist on saadud postide tarvis ka paindemomendid, millega on läbisurumisarvutuses arvestatud. Lisaks büroohoonele on koostatud arvutusmudel tüüpse parkimismaja kahe tasapinnalise raami tarvis, et hinnata postides tekkivaid sisejõudusid, ennekõike paindemomente. Standartne staatikaarvutus annab postidesse suured paindemomendid, mis omakorda põhjustavad postide pragunemist ja sellest lähtuvat paindejäikuse vähenemist. Arvutusmudelis on korrigeeritud postide jäikust pragunemise- ja lisaks roome mõju arvestades ning selle tulemusena on saadud tunduvalt väiksemad paindemomendid. See võimaldab oluliselt vähendada armeeringu vajadust.

Abstract [en]

The aim of this thesis is to assess the performance of the walls and columns of an eight-storey office building with a monolithic concrete frame in different load conditions and to generate hypothetical calculation results and provide reinforcements to the core rigidity of the building that would correspond to the obtained results, based on the computationally required reinforcement and structural requirements. The building under observation has eight floors, with planned axis dimensions of 7 x 8 = 56 m and 3 x 8 = 24 m. The locations of the rigid walls are varied as follows: the rigid walls are situated both symmetrically in the middle of the building at different distances and completely at the border of the building. The internal force of the walls in one wind direction is calculated in the work. The wind load in the other direction is not taken into consideration, because it is received by other walls that are perpendicular to the observed ones. In the event of at least a symmetrical load, adding them to the calculated direction would not significantly alter the result, since the rigidity of the cross walls is several times lower than the stiffness of the walls developed in the wind direction. The above-mentioned calculation results have also been compared with the results of a calculation model compiled in Autodesk Robot Structural Analysis programme. Depending on the calculations, it became evident that the location of the walls significantly impacts their loads and internal forces. In the case of rigid walls located symmetrically within the building, it is crucial to keep the distance between the walls as large as possible. By doing so, it reduces the adverse effects of an asymmetric load. There are longitudinal tensions in the walls caused by the vertical and the horizontal load. At one end of the wall, compressive tensions add up, while at the other, in the event of a high wind moment and insufficient vertical pressure, tensile stress-strains may occur. For all selected walls, the upper three floors remain fully compressed and there are no tensile stress-strains in the walls. The highest tensile and compressive stresses may be found on the lower floors, the stresses on the upper floors decrease. It is expedient to take this fact into account in the construction solution and to design the wall thickness and reinforcement in compliance with the internal forces. The dimensions of the foundations are fixed based on the load-bearing capacity of the soil. Upon determining the dimensions, the height of the top surface of the foundation was assumed to be 0.6 m from the floor surface and the thickness of the base was increased as needed. Parallelly, the structural depth also incremented. The calculation results showed a beneficial effect of increasing the distance between the walls and the symmetrical position. The two walls on one side of the building need such a solid foundation for the approach discussed in the work that it will probably be possible to come up to more practical solutions. The first advantage is to change the rigidity scheme of the building, to place the walls symmetrically with respect to the building or to add a new rigid wall to the other end of the building. The manually calculated vertical and horizontal forces of the office building columns have been compared with those achieved by the calculation model. The model also provides bending moments for the columns, which must be considered in the calculation of structures in compression. In addition to the office building, an equation model has been developed for the two planar frames of a typical parking garage in order to estimate the internal forces generated in the columns, in particular the bending moments. Standard static calculation gives the columns high bending moments, which in turn bring about the cracking of the columns and consequently reduce the flexural rigidity. In the equation model, the rigidity of the columns has been adjusted, taking into account the impact of cracking and, in addition, creep, and as a result, fairly lower bending moments have been obtained, which in turn allows to considerably decrease the need for reinforcement.

Item Type: thesis
Advisor: Peeter Paane
Subjects: Construction > Building Construction > Structural Design > Reinforced Concrete Structures
Construction > Building Construction > Structural Design
Divisions: Institute of Construction > Building Construction
Depositing User: Allar Taimsaare
Date Deposited: 04 Jun 2020 08:00
Last Modified: 04 Jun 2020 08:00
URI: https://eprints.tktk.ee/id/eprint/5168

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