CC BY
16
УДК 624.016
DOI: 10.30838/J.BPSACEA.2312.220920.176.685
INVESTIGATION OF THE STRESS-STRAIN STATE OF HYBRID TIMBER-REINFORCED CONCRETE MULTI-STOREY BUILDINGS
SHEKHORKINA S.Yev.1*, Cand. Sc. (Tech.), Assoc. Prof., ADIL JABBAR ABBAS 2, Postgraduate Student, NIKIFOROVA T.D.3, Dr. Sc. (Tech.), Professor
1 Department of Reinforced-Concrete and Masonry Structures, State Higher Education Institution"Prydniprovska State Academy of Civil Engineering and Architecture", 24-a, Chernyshevskoho St., 49600, Dnipro, Ukraine, tel.+38 (095) 021-84-44, email: S [email protected], ORCID ID: 0000-0002-4377-3746
2 Department of Reinforce-Concrete and Masonry Constructions, State Higher Education Institution "Prydniprovska State Academy of Civil Engineering and Architecture", 24-a, Chernyshevskoho Str., 49600, Dnipro, Ukraine, e-mail: [email protected]
3 Department of Reinforce-Concrete and Masonry Constructions, State Higher Education Institution"Prydniprovska State Academy of Civil Engineering and Architecture", 24-a, Chernyshevskoho St., 49600, Dnipro, Ukraine, e-mail: [email protected], ORCID ID: 0000-0002-0688-2759
Abstract. Problem statement. The use of timber in multi-storey buildings is a promising direction in terms of reducing the impact of the construction industry on the environment. Hybrid buildings represent a rational combination of timber as the main structural material and reinforced concrete for spatial stability providing. At present time there are no recommendations for the choice of structural system of multi-storey hybrid buildings, the issues of joint work and stressstrain state of load-bearing structures of timber and reinforced concrete in the spatial system of multi-storey buildings are insufficiently studied. The article is devoted to the analysis of the stress-strain state of hybrid timber-reinforced concrete multi-storey buildings. In the study, the number of storeys of the building was accepted of 5, 10 and 15 floors. The type of the joints between of the load-bearing structures and the method of ensuring spatial rigidity, namely the number and location of the shear walls and the rigidity core, were varied. For each option, a spatial finite element model was compiled and a static load analysis was performed in accordance with the requirements of current design standards. Results and conclusion. The data on the magnitude of the horizontal displacements of the upper part of the building, as well as the maximum values of the forces from adverse combinations of loads, were obtained. The analysis of the stability of the building and the bearing capacity of timber columns were performed. Based on the results obtained, the recommendations are proposed for choosing a structural scheme, a method for ensuring the spatial rigidity of a building, as well as assigning cross-sectional dimensions at the initial stage of the design of a hybrid timber-reinforced concrete multi-storey building.
Keywords: hybrid buildings; timber; reinforced concrete; stress-strain state; displacements
ДОСЛ1ДЖЕННЯ НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ Г1БРИДНИХ ДЕРЕВО-ЗАЛ1ЗОБЕТОННИХ БАГАТОПОВЕРХОВИХ БУДШЕЛЬ
ШЕХОРК1НА С. е.1*, канд. техн. наук, доц., АД1Л ДЖАББАР АББАС 2, acnip, Н1К1ФОРОВА Т. Д.3, докт.
техн. наук, професор
1 Кафедра залiзобегонних та кам'яних конструкцш, Державний вищий навчальний заклад «Приднгпровська державна академiя будгвництва та архггектури», вул. Чернишевського, 24-а, 49600, Дшпро, Украша, тел. +38 (095) 021-84-44, e-mail: S [email protected], ORCID ID: 0000-0002-7799-2250
2 Кафедра затзобетонних та кам'яних конструкцш, Державний вищий навчальний заклад «Придшпровська державна академш будгвництва та архггектури», вул. Чернишевського, 24-а, 49600, Дншро, Украша, e-mail: adil. adil249@yahoo .com
3 Кафедра затзобетонних та кам'яних конструкцш, Державний вищий навчальний заклад «Придшпровська державна академш будгвництва та архггектури», вул. Чернишевського, 24-а, 49600, Дншро, Украша, e-mail: [email protected], ORCID ID: 0000-0002-0688-2759
Анотащя. Постановка проблеми. Пбридш конструкци, завдяки рацюнальному поеднанню властивостей, дозволяють збшьшити несну здатшсть та просторову жорстшсть будiвля, що дае можливють багатоповерхового будiвництва з використанням деревини як основного конструкцшного матерiалу. Застосування деревини в багатоповерховому будiвництвi е перспективным напрямком з точки зору зменшення впливу будавельно! галузi на навколишне середовище. На сьогодшшнш день ввдсутт рекомендацп щодо вибору конструктивно! системи багатоповерхових будiвель пбридно! системи, питання стльно! роботи та напружено-деформованого стану
несучих конструкцш з деревини та з^зобетону в просторовш системi багатоповерхово! будiвлi дослiдженi недостатньо. Мета cmammi полягае у дослщженш напружено-деформованого стану гiбридних дерево-залiзобетонних багатоповерхових будинк1в. Для аналiзу було прийнято квадратний у планi будинок-прототип. Щд час моделювання варшвалася кшьшсть поверхiв (5, 10 та 15), тип сполучення м1ж несучими конструкщями (колонами та балками) та споаб забезпечення просторово! жорсткостi (кiлькiсть та розташування дiафрагм та ядра жорсткосл). Для кожного варiанту з використанням програмного комплексу Л1РА - САПР була складена просторова ск1нченноелементна модель та проведено статичний розрахунок ввдповщно до вимог чинних стандартiв проектування. Результати та висновки. Проведена оцшка впливу конструктивно! системи, поверховостi та способу забезпечення просторово! жорсткосл на напружено-деформований стан багатоповерхових гiбридних будавель. Отриманi данi щодо горизонтальних перемщень свiдчать про те, що просторова жорстшсть забезпечуеться: для 5 та 10-поверхових будiвель для всiх варiантiв, крiм шарнiрних з'еднань елеменпв каркаса без додаткових заходiв щодо забезпечення просторово! жорсткосл; для 15-поверхово! будiвлi для жорстких з'еднань елементiв та для шаршрних з'еднань з ядром жорсткосл або чотирма дiафрагмами. За результатами аналiзу коефiцiента використання несучо! здатностi колон було встановлено, що прийнял розмiри поперечного перерiзу забезпечують несну здатнiсть вiдповiдно до вимог чинних нормативних документiв. Виняток становить 5-поверхова будiвля з шарнiрними з'еднаннями, а також 10-поверхова будiвля з жорсткими стиками м1ж елементами (коефщенти використання 1,96 та 1,11, ввдповвдно). Запропонованi рекомендацi! щодо вибору конструктивно! схеми, способу забезпечення просторово! жорсткосл будiвлi, а також призначення розмiрiв поперечного перерiзу на початковому етат проектування гiбридно!' дерево-залiзобетонно!' багатоповерхово! будiвлi.
Ключовi слова: ггбридт будгвлг; деревина; зал1зобетон; напружено-деформований стан; перемгщення
ИССЛЕДОВАНИЕ НАПРЯЖЕННО-ДЕФОРМИРОВАННОГО СОСТОЯНИЯ ГИБРИДНЫХ ДЕРЕВО-ЖЕЛЕЗОБЕТОННЫХ МНОГОЭТАЖНЫХ ЗДАНИЙ
ШЕХОРКИНА С. Е.1*, канд. техн. наук, доц., АДИЛ
ДЖАББАР АББАС 2, аспир.,
НИКИФОРОВА Т. Д.3, докт. техн. наук, проф.
1 Кафедра железобетонных и каменных конструкций, Государственное высшее учебное заведение «Приднипровская государственная академия строительства и архитектуры», ул. Чернышевского, 24-а, 49600, Днипро, Украина, тел. +38 (095) 021-84-44, e-mail: S [email protected], ORCID ID: 0000-0002-7799-2250
2 Кафедра железобетонных и каменных конструкций, Государственное высшее учебное заведение «Приднипровская государственная академия строительства и архитектуры», ул. Чернышевского, 24-а, 49600, Днипро, Украина, e-mail: adil. adil249@yahoo .com
3 Кафедра железобетонных и каменных конструкций, Государственное высшее учебное заведение «Приднипровская государственная академия строительства и архитектуры», ул. Чернышевского, 24-а, 49600, Днипро, Украина, e-mail: [email protected], ORCID ID: 0000-0002-0688-2759
Аннотация. Постановка проблемы. Использование древесины в многоэтажных домах является перспективным направлением с точки зрения снижения воздействия строительной отрасли на окружающую среду. Гибридные здания представляют собой рациональное сочетание древесины как основного конструкционного материала и железобетона для обеспечения пространственной жесткости. В настоящее время отсутствуют рекомендации по выбору конструктивной системы многоэтажных гибридных зданий, вопросы совместной работы и напряженно-деформированного состояния несущих конструкций из дерева и железобетона в пространственной системе многоэтажных зданий недостаточно изучены. Статья посвящена анализу напряженно-деформированного состояния гибридных железобетонных многоэтажных зданий. Для анализа было принято квадратное в плане здание. При моделировании варьировалась количество этажей (5, 10 и 15), тип сопряжения между несущими конструкциями и способ обеспечения пространственной жесткости. Для каждого варианта была составлена пространственная конечноэлементная модель и выполнен статический расчет в соответствии с требованиями действующих стандартов проектирования. Результаты и выводы. Получены данные о величине горизонтальных перемещений верхней части здания, а также о максимальных значениях усилий от неблагоприятных сочетаний нагрузок. Проведен анализ устойчивости здания и несущей способности деревянных колонн. На основании полученных результатов предложены рекомендации по выбору конструктивной схемы, способа обеспечения пространственной жесткости здания, а также назначению размеров поперечного сечения на начальном этапе проектирования гибридного дерево-железобетонного многоэтажного здания.
Ключевые слова: гибридные здания; древесина; железобетон; напряженно-деформированное состояние;
перемещения
Introduction. The traditional construction industry has a negative impact on the environment in many ways (greenhouse gas emissions, waste accumulation, the use of nonrenewable resources, etc.). Timber has several advantages in terms of sustainable development and circular economy. Awareness of global environmental problems and the search for ways to solve them contributed to the emergence of innovative solutions based on timber as a structural building material.
Currently, new solutions are being developed for hybrid structures for the construction of both multi-story and high-rise buildings, in which timber is the main structural material (up to 80%), and reinforced concrete or steel is used to increase resistance to external loads. The following projects can be cited as examples: LifeCycle Tower ONE, Panorama Giustinelli, Cenni di Cambiamento, Murray Grove, Origine Condos, Brock Commons etc. [1-5]. In research [6], the authors substantiate the use of the developed hybrid system for buildings with a height of 10...30 floors. Structural system consists mainly of timber elements that are used to arrange the central core and stiffness diaphragms, ceilings, load-bearing walls and columns. Analyzing the above projects, it can be concluded that the spatial rigidity is achieved due to the regular location of the load-bearing structures in the plan and in the height of the building, as well as symmetrically located in the plan of the shear walls and the rigidity core.
Despite the growing popularity of multistorey buildings with a hybrid structure, comprehensive regulatory and technical documentation for the calculation and design of this type of building currently does not exist. It is necessary to develop scientifically based recommendations for choosing the structural system of the building at the initial stage of design, preliminary assignment of geometric parameters and strength characteristics of the material of the load-bearing structures.
The purpose of this study is to analyze the stress-strain state of hybrid timber-reinforced concrete multi-storey buildings depending on the number of storeys and the method of providing the spatial rigidity.
Materials and methods. For the analysis of
the stress-strain state of multi-storey buildings of a hybrid structure, a prototype building was chosen. The spacing of frames was adopted of 5 m in both directions. The number of floors was varied of 5, 10, and 15 storey. The storey height for all options was 3 m. Thereby the height of the buildings was 15, 30 and 45 m, respectively. Two types of joints between horizontal and vertical load-bearing elements were considered -hinge and rigid. To ensure the spatial rigidity of the building, the use of vertical shear walls and a rigidity core were considered. Layout schemes for each option are shown on Figure 1.
a
Fig. 1. Layouts of multi-storey buildings with a hybrid structure: a) without rigidity elements; b) 2 shear walls; c) 4 shear walls; d) rigidity core
The beams and columns of glued laminated timber and the shear walls and rigidity core of reinforced concrete were adopted as load bearing elements. The physical and mechanical characteristics of materials and the parameters of the cross section of the structural elements of the building are shown in Table 1.
Table 1
Physical and mechanical characteristics of materials and parameters of the cross section of the structural elements
Element Cross section dimensions, mm Strength class Density, kg/m3 Modulus of elasticity, GPa
1 2 3 4 5
Column 250x250 300x300 400x400 GL28h 410 12.6
Beam 250x500 GL28h 410 12.6
c
End of Table 1
1 2 3 4 5
Shear wall / rigidity core 250 C20/25 2500 30.0
An analysis of the stress-strain state in accordance with the requirements of the current design standards was carried out for the adopted options of the building. Loads on building elements were determined in accordance with the requirements of [7]. The design value of the self-weight of the floor and floor coverings was taken 1.5 kN/m2, the imposed load on the floor elements - 1.95 kN/m (as for a residential building), and the snow
load - 1.6 kN/m2 (for wind load zone III according to Ukrainian wind map). The design values of the wind load on the vertical frames considering the spacing of 5 m are presented in Table 2. A diagram of the variation of wind load depending on height is shown on Fig. 2.
Table 2
The design values of the wind load
Storeys Height, Wind load, [kN/m]
[m] positive negative
1 < 5 1.368 1.206
5 15 2.736 2.052
10 30 3.83 2.875
15 45 4.63 3.47
50
s40
Ü30
S 20
w 10 0
0 1 2 3 4 5 Wind load, kN/m.
Fig. 2. A diagram of the variation of wind load depending on height
For each variant of the building, a 3D finite element model was compiled using LIRA-SAPR commercial software. Beams and columns were modelled with elements of the FE 10 type (universal spatial rod FE). The diaphragms and stiffness core were set by elements of type FE 41 (universal rectangular FE shell). The following loads were applied to the elements of the model
in accordance with the determined load values: 1 - self-weight of the construction elements (permanent action); 2 - imposed on the floor structure (variable); 3 - snow load; 4 - wind load. The models obtained are illustrated on the 5 storey building variant in Figure 3.
a)
c) 1 d)
Fig. 3. 3D finite element models obtained (for the 5 storey variant): a) without rigidity elements; b) 2 shear walls; c) 4 shear walls; d) rigidity core
Results and discussion. As a result of the static calculation of spatial models, data were obtained on the values of the horizontal displacements of the upper part, i.e. the deviation of the building from the vertical axis. The values obtained were used to assess the spatial stability of the building. The maximum allowable horizontal displacements of the upper part of the multi-storey building according to [8] are fu = h/500 (where h is the total height of the building). Therefore for the variants considered this value is limited to 30 mm for 5 storey; 60 mm for 10 storey and 90 mm for 15 storey.
Diagrams of horizontal displacements caused by the wind load along the height of the building are shown on Figure 4.
Maximum values of internal forces caused by unfavorable load combinations were obtained for each variant of buildings. Using these data, the analysis of the load-bearing capacity (strength and stability) was performed for timber columns as the most loaded elements. The maximum values of internal forces and load-bearing capacity utilization rate of timber columns are presented in Table 3 and on Figure 5.
The data obtained on the horizontal displacements of the considered building types indicate that spatial rigidity is provided:
- for 5 and 10-storey buildings for all variants, except for the hinge joints of frame elements without additional measures for spatial rigidity providing;
- for a 15-storey building for rigid joints of frame elements and for hinge joints of elements
35
30
B 25
¡3 20
15
Q 10
r*'
S
/ (Zx.i r-ri r.r.1!
50
40
30
J3
CO
Q 20
10
with a rigidity core. It should be noted that in the case of four stiffness diaphragms, horizontal displacements of the upper point of the building are approximately equal to the maximum allowable values.
120
J X r
/ o rill
w
100
60
o 40
20
23 Storey
b
4 6 Storey
8 10
I
1
t
/ 1 / r Jp
* If f
J •¡T ft
*
5 10 Storey
15
1 2 3 4 -5 max allowable
Fig. 3. Diagrams of horizontal displacements caused by the wind load along the height of the building: a) for a 5-story building; b) for a 10-story building; c) for a 15-story building: 1 - hinge joints without rigidity elements; 2 - rigid joints without rigidity elements; 3 - hinge joint + 2 shear walls; 4 - hinge joint + 4 shear walls; 5 - hinge joint + rigidity core
Table 3
Maximum values of internal forces and load-bearing capacity utilization rate of timber columns
Number of Cross-section Type of Internal forces combination Load-bearing capacity
storeys size, mm building N, kN M, kNm utilization rate
1 -356,25 63,84 1,963
2 -353,6 13,5 0,725
5 250x250 3 -356,25 8,736 0,611
4 -356,25 5,47 0,531
5 -356,25 8,46 0,604
2 -780.7 39.04 1.11
10 300x300 3 -775.8 12.4 0.730
4 -775.8 6.74 0.65
5 -775.8 10.73 0.706
2 -1153.8 72.23 0.907
15 400x400 3 -1163.69 18.55 0.600
4 -1163.7 9.74 0.549
5 -1163 13.76 0.572
b c
Fig. 5. Diagrams of load-bearing capacity utilization rate of timber columns: a) for a 5-story building; b) for a 10-story building; c) for a 15-story building: 1 - hinge joints without rigidity elements; 2 - rigid joints without rigidity elements; 3 - hinge joint + 2 shear walls; 4 - hinge joint + 4 shear walls;
5 - hinge joint + rigidity core
5
0
0
0
0
1
4
5
0
2
0
a
c
According to the results of the analysis of the load-bearing capacity utilization rate of the columns, it was found that the accepted dimensions of the cross sections of the columns provide load-bearing capacity in accordance with the requirements of current regulatory documents. The exception is the 5-story building with hinge joints (utilization rate 1.96), as well as a 10-story building with rigid joints between elements (utilization rate 1.11).
Thus, at the initial stage of the design of a hybrid timber-reinforced concrete multi-storey building, the following structural schemes can be recommended. For a 5-storey building it is possible to use rigid type of joint, as well as hinge but with the application of shear walls or a rigidity core; the dimensions of the cross-section of the columns should be assigned at least 250x250 mm. For a 10-story building the dimensions of the cross-section of the columns 300x300 mm and a scheme with hinge type of joints with a shear walls or rigidity core should be adopted. For a 15-story building, the cross-sectional dimensions of the columns should be taken at least 400x400 mm, as well as a scheme with rigid joints of frame elements or hinge joints in combination with a stiffness core is recommended.
Conclusions. The analysis of the stress-
strain state of hybrid timber-reinforced concrete multi-storey buildings depending on the number of storeys and the method of ensuring spatial rigidity in accordance with the requirements of current standards has been performed. The buildings of 5, 10 and 15 storey with rigid and hinge type of joints between frame elements, as well as different modes of spatial stiffness providing (various configuration of shear walls and rigidity core) were considered.
3D finite-element model for each type of buildings were developed using available commercial software. As a result of the static calculation of the models, data were obtained on the values of the horizontal displacements of the upper part of the building, as well as the maximum values of internal forces caused by unfavorable load combinations. Using these data, an analysis of the spatial stability of the building and the load-bearing capacity of timber columns as the most loaded elements was performed.
Based on the results obtained, recommendations were proposed for choosing a structural scheme, a method for providing the spatial rigidity of a building, as well as assigning cross-sectional dimensions at the initial stage of the design of a hybrid timber-reinforced concrete multi-storey building.
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Hagmm.na go pega^n 18.09.2020.
