The timber roof structure of the church central nave in Niksic

U radu je prikazano rešenje drvene konstrukcije centralnog dela krova crkve, u gradu Nikšiću u Crnoj Gori. Centralni deo krova je oblika pravilne piramide nad osmougaonom osnovom. Osnovni konstruktivni sistem čini osam zakrivljenih nosača od drveta, koji se oslanjanju u uglovima osmougaonika i vezuju u jednoj tački na vrhu krova. Iznad ovih nosača, u njihovoj ravni su dodati drveni kosi štapovi, kako bi se formirao piramidalni oblik krova. S obzirom na zakrivljenu formu nosača osnovnog konstruktivnog sistema, projektom konstrukcije je predviđeno lepljeno lamelirano drvo za osnovne elemente konstrukcije krova. Rešenje obuhvata prikaz svih elemenata konstrukcije krova, po hijerarhiji prenošenja opterećenja, kao i rešenje metalnog okova za međusobnu vezu drvenih elemenata.The paper presents the solution of the timber roof structure of the central nave in the town of Nikšić in Montenegro. The central part of the roof is shaped like a regular pyramid over an octagonal base. The basic structural system consists of eight curved timber girders, which are supported in the corners of the octagon and are connected at one point at the top of the roof. Above these girders, in their plane, the secondary supporting structure was added, in order to form the pyramidal shape of the roof. Considering the curved shape of the girders of the basic structural system, the design of the structure foresees glued laminated timber for the basic elements of the roof structure. The solution includes a presentation of all elements of the roof construction, according to the hierarchy of load transfer, as well as a solution of steel connectors for the mutual connection of timber elements

Analiza dinamičkih obilježja i krutosti pri savijanju podnih ploča od križno lameliranog drva provedena metodom konačnih elemenata

The aim of this paper is to present numerical investigations of dynamic characteristics and bending stiffness for cross laminated timber floor panels with and without service openings. Five-layer panels with the outer layers oriented in the longitudinal direction of the panel have been analyzed. In order to explore the full potential of this floor system using a limited number of measurements and structural tests, models based on the finite element method have been proposed, validated against experimental results and then used to investigate the effect of opening position in the floor on main structural performance parameters. The results showed that, when the need for additional service opening appears, a slight decrease of the main structural characteristics of the cross laminated timber floor panels is achievable with an adequate geometrical position of the opening in the floor.Cilj ovog rada jest prikaz numeričkog modela dinamičkih obilježja i krutosti pri savijanju podnih ploča od križno lameliranog drva (CLT) sa servisnim otvorom i bez njega. Analizirane su peteroslojne ploče s vanjskim slojevima orijentiranim u uzdužnom smjeru ploče. Kako bi se uz pomoć ograničenog broja mjerenja i mehaničkih ispitivanja istražio puni potencijal takvoga podnog sustava, predloženi su modeli utemeljeni na metodi konačnih elemenata koji su validirani u usporedbi s eksperimentalnim rezultatima te primijenjeni za istraživanje utjecaja položaja otvora u podu na glavne parametre ponašanja konstrukcije. Rezultati su pokazali da se odgovarajućim pozicioniranjem naknadnog otvora u podu može postići vrlo malo smanjenje glavnih mehaničkih svojstava podnih ploča od CLT-a

Vibrations of Cross-Laminated Timber Floors

U radu su ispitane vibracije peteroslojnih međukatnih križno lameliranih drvenih panela visine 14 cm izazvane ljudskim djelovanjem. Analizirana su tri međukatna panela identičnih visina, ali s različitim kombinacijama debljine lamela u križnim slojevima variranjem njihovih raspona. Navedeni su bitni kriteriji što ih pri projektiranju treba zadovoljiti međukatna konstrukcija da bi se osiguralo njezino prihvatljivo ponašanje u uvjetima dinamičkog opterećenja. Izračun efektivne krutosti na savijanje panela obavljen je Gamma metodom, K-metodom i Kreuzingerovom analogijom. Analitički je određena osnovna frekvencija vibriranja svakog panela, kao i maksimalni progib zbog jedinične statičke sile, a dobiveni su rezultati uspoređeni s vrijednostima dobivenim modalnom i statičkom analizom u programskom paketu Ansys. Svi su dobiveni podatci uspoređeni s važećim kriterijima i selektirani su paneli koji ispunjavaju kriterije sa stajališta graničnog stanja uporabivosti. Rezultati su pokazali da su analizirani međukatni paneli raspona do 4,5 m prihvatljivi sa stajališta adekvatnoga dinamičkog ponašanja pri ljudskom djelovanju. Rezultati su također pokazali da su kombinirani kriterij i kriterij maksimalnoga dopuštenog progiba zbog jedinične statičke sile znatno stroži od kriterija minimalne vrijednosti osnovne frekvencije vibriranja.This paper investigates the vibrations caused by human action of five-layer cross-laminated timber panels with a height of 14 cm. Analysis is made of three floor panels of identical height, but with different combinations of thicknesses of the laminas in cross-layers, varying their spans. The longitudinal layers of the panels have better physical and mechanical characteristics than transverse layers. The relevant criteria to be observed in floor construction at the designing stage are specified in order to ensure acceptable behavior regarding the dynamic load. Limit values are also given. As it is very difficult to determine the threshold of human acceptability, since vibrations that someone finds disturbing do not have to be disturbing for others, the relevant criteria used in the work has been chosen on the basis of the highest representation in the literature: Natural Frequency Limit, Unit Load Deflection Limit and the Combined Criterion. Calculation of the effective bending stiffness of the panel was performed using Gamma method, K-method and Kreuzinger analogy. The natural frequency of each panel was determined analytically, and so was the maximum deflection due to unit static force and the obtained results were compared with the values obtained by modal and static analysis in the Ansys software package. All the obtained data were compared with the valid criteria, and panels that meet the criteria in terms of the serviceability limit state were selected. The results showed that the analyzed floor panels of the span up to 4.5 m are acceptable in terms of adequate dynamic behavior related to human action according to all criteria. Also, the results showed that the Combined Criterion and the Unit Load Deflection Limit are significantly stricter due to the unit static force compared to the Natural Frequency Limit. If the minimum required natural frequency of the CLT panel were accepted with a value of 8 Hz, which corresponds to the milder recommendations in the available literature, the spans could go up to 6 m. On the basis of the obtained results, it can be concluded that in the design of floor structures, in addition to static stability, an adequate dynamic response to the initiative caused by everyday human activities must be provided. The results also show that the analyzed floor CLT panels can be very successfully applied in the floor constructions of residential and commercial buildings, provided that the required dynamic calculations are made

Timber frame truss constructions in the LKV system

U radu su prikazani okvirni drveni rešetkasti nosači u sistemu LKV i njihova primena kod trovodnih krovova. Posebna pažnja je posvećena projektovanju bočnog sektora krova, u funkciji statičke visine nosača i veličine pripadajućeg opterećenja. Dati su osnovni principi funkcionalne organizacije karakterističnih sektora krova, što je od značaja za definisanje geometrije svih nosača koji formiraju drvenu strukturu. Unifikacija prefabrikovanih elemenata je od značaja za proizvodnju i ekonomičnost drvene strukture. U sklopu drvene strukture su takođe dati položaj i geometrija spregova za ukrućenje, kao sastavnih elemenata strukture krova

Torsional buckling of thin-walled beams in presence of bimoment induced by axial loads

U članku je proučen utjecaj bimomenta na stabilnost tankostjenog štapa s otvorenim poprečnim presjekom uslijed vanjskog aksijalnog opterećenja. Primjenom principa virtualnih pomjeranja izvedene su diferencijalne jednadžbe deformiranog tankostjenog elementa u skladu s klasičnim pretpostavkama Vlasova. Pokazano je da kod poprečnih presjeka koji nemaju os simetrije bimomenat može značajno utjecati na uvojnu kritičnu silu. Dobiveni rezultati su provjereni primjenom programa ANSYS.In this paper the influence of the bimoment induced by external axial loads on the elastic torsional buckling of thin-walled beams with open cross-section is studied. The governing differential equations of a deformed thin-walled beam consistent with Vlasov’s classical assumptions are derived applying the principle of virtual displacements. It is shown that in the cross sections with lack of symmetry the bimoment can considerably affect the torsional buckling load. The obtained results are verified using ANSYS finite element software

Dynamic characteristics of CLT panels: Computer modelling and simulations

The fundamental vibration frequency and deflections due to the unit static force of the cross-laminated timber panels of different heights and spans were calculated. The calculation of the effective flexural rigidity was performed by the Gamma method. Obtained values are compared with the values obtained by modeling the construction in the Ansys software package. Three types of floor panels were analyzed with the same combinations of layer thicknesses in the cross section, but with different number of layers. The panels are 4, 5 and 6 meters long and 1 meter wide. Based on the results, recommendations have been made in accordance with current criteria that define the acceptable behavior of lightweight floor structures in relation to vibrations caused by human action

Reinforcement of steel cylindrical silo due to repurpose of technology and loading

During the exploitation of the steel cylindrical silo there was a repurpose of construction that required the need for creating a revision on the lower part of the silo. In addition, due to the change in the type of material stored in the silo, the load was increased. An analysis of all relevant impacts has begun to determine the actual stress and strain state on the structure. The construction is modelled in the Abaqus software package. Based on static influence, the necessary reinforcements are foreseen and the construction is dimensioned according to European regulations - Eurocodes

LKV nosači sa paralelnim pojasnim štapovima i njihova primena

The paper presents wooden trusses with parallel chords designed in the System of lightweight roof girders - LKV system, and their application in the construction of buildings. The basic static systems of these girders, their characteristics, as well as numerous examples of constructed wooden structures are presented. In the structure of the wooden constructions, these girders can play the role of bearing elements for receiving gravity loading, as well as the role of lateral bracing frame.U radu su prikazani nosači sa paralelnim pojasnim štapovima projektovani u Sistemu LKV, i njihova primena u konstrukcijama objekata visokogradnje. Prikazani su osnovni statički sistemi ovih nosača, njihove karakteristike, kao i brojni primeri izvedenih drvenih konstrukcija primenom ovih oblika nosača. U strukturi drvene konstrukcije, ovi nosači mogu imati ulogu nosivih elemenata za prijem gravitacionog opterećenja, kao i ulogu spregova protiv vetra i spregova za ukrućenje

Design steel spherical tank height H = 44m according to Eurocode

This paper presents the design of the steel water tower with spherical water tank height H = 44m. Spherical tank is located at the top of the steel tubular column, with diameter F = 128cm. The construction of the water tower was modeled using the ABAQUS software package, to give a realistic picture of the stress-strain states in all points of the tank shell and the tubular column. Analysis of the load of construction was carried out based on European standards, with special attention to the influence of the earthquake on the spherical tank

Nosivost metalnоg konektera u zavisnosti od položaja i geometrije eksera

This paper presents results of the experimental determination of the load-bearing capacity of structural timber connections realized by nail metal connector plates as a function of nail location, length and diameter. Three different diameters of the nails have been used, specifically 2.0, 2.5, and 3.1 mm. The length of the metal nails in connectors has been determined after the detailed analysis, and kept at 20 mm during the experimental research. Nails distribution over the connector plate is such that it forms the series of equilateral triangles, so that a side of the triangle equals five times the diameter of the nails used. Preceding the testing, and while using the above listed parameters certain analysis has been done. In order to experimentally determine the load-bearing capacity of the nail metal connectors, the penetration depth, i.e. the length of the nails has been kept constant, while using three different nail diameters. The testing has been done on multiple samples in the accordance with Eurocode 5.U radu je prikazano eksperimentalno određivanje nosivosti veza ostvarenih ekserastim metalnim konekterima, u funkciji položaja, dužine i prečnika eksera. Ekserasti konekteri koji su podvrgnuti ispitivanju su napravljeni upotrebom eksera dužine 20 mm, prečnika 2.0 mm, 2.5 mm i 3.1 mm. Raspored eksera po površini metalne ploče konektera je takav da oni formiraju mrežu jednakostraničnih trouglova, gde je dužina stranice trougla jednaka petostrukoj vrednosti prečnika eksera. U skladu sa navedenim parametrima, urađene su određene analize koje su prethodile eksperimentalnom ispitivanju. Eksperimentom su utvrđene nosivosti ekserastog metalnog konektera, upotrebom tri različita prečnika eksera, ali iste dužine, odnosno iste dubine zabijanja eksera u drvo. Eksperiment je izveden na više uzoraka, u skladu sa Evrokodom 5