A two-level macroscale continuum description with embedded discontinuities for nonlinear analysis of brick/block masonry

A great proportion of the existing architectural heritage, including historical and monumental constructions, is made of brick/block masonry. This material shows a strong anisotropic behaviour resulting from the specific arrangement of units and mortar joints, which renders the accurate simulation of the masonry response a complex task. In general, mesoscale modelling approaches provide realistic predictions due to the explicit representation of the masonry bond characteristics. However, these detailed models are very computationally demanding and mostly unsuitable for practical assessment of large structures. Macroscale models are more efficient, but they require complex calibration procedures to evaluate model material parameters. This paper presents an advanced continuum macroscale model based on a two-scale nonlinear description for masonry material which requires only simple calibration at structural scale. A continuum strain field is considered at the macroscale level, while a 3D distribution of embedded internal layers allows for the anisotropic mesoscale features at the local level. A damage-plasticity constitutive model is employed to mechanically characterise each internal layer using different material properties along the two main directions on the plane of the masonry panel and along its thickness. The accuracy of the proposed macroscale model is assessed considering the response of structural walls previously tested under in-plane and out-of-plane loading and modelled using the more refined mesoscale strategy. The results achieved confirm the significant potential and the ability of the proposed macroscale description for brick/block masonry to provide accurate and efficient response predictions under different monotonic and cyclic loading conditions.

Opening Area Effect of Core Type Shear Wall in Hospital Building with Highest Importance Factor

Multi-storey buildings have fascinated mankind from the beginning of civilization, their construction being initially for defence and subsequently for ecclesiastical purposes. These tall buildings because of its height, is affected by lateral forces due to wind or earthquake actions tends to snap the building in shear and push it over in bending. In general, the rigidity (i.e. Resistance to lateral deflection) and stability (i.e. Resistance to overturning moments) requirement become more important. Shear walls (Structural walls) contribute significant lateral stiffness, strength, and overall ductility and energy dissipation capacity. In many structural walls a regular pattern of openings has to be provided due to various functional requirements such as to accommodate doors, windows and service ducts. Such type of openings reduces the stiffness of the shear wall to some extent depending on the shape and size of the opening. In the present parametric study, efforts are made to investigate and critically assess the effects of various size of openings in shear walls on the responses and behaviours of multi-storey buildings also Opening Area Effect of Core Type Shear Wall In Hospital Building with Highest Importance Factor. Many G+20 storey prototype buildings with different types of openings in shear wall with and without incorporating the volume of shear wall reduced in the boundary elements are analysed using software Staad-Pro using Response spectrum method (1893-2016). Overall analysis shows that the most efficient case for this study has been HIF5. The hospital building can be survived with highest importance with the value of I = 1.5 as per IS 1893:2016 for opening area effect of core type shear wall. It can also be recommended that upto 25% opening will be possible without any seismic damage. Keywords: Shear wall, Opening Criteria, Highest Importance Factor, Multi-storey Hospital Building

Novel Dual Walling Cob Building: Dynamic Thermal Performance

This paper emphasizes the experimental and numerical study of new cob mixes used for insulation and load bearing wall elements. The experimental study provides complete datasets of thermal properties of the new walling materials, using cob with density ranging from 1107 kg/m3 to 1583 kg/m3 for structural walls and less than 700 kg m−3 for insulation walls. Various mixes of French soils and fibres (reed, wheat straw, hemp shiv, hemp straw, and flax straw) with different water contents are studied. The lowest average thermal conductivity is obtained for the structural cob mix prepared of 5% wheat straw and 31% of water content. The insulation mix, prepared with 25% reed and 31% water content, has the lowest thermal conductivity. Investigation of diffusivity, density, and heat capacity shows that, when thermal conductivity is lower than 0.4 W m−1 K−1, the decrease in cob density leads to better insulation values and higher heat capacity. Little variation is noticed regarding the density and heat capacity for cob mixes with thermal conductivity higher than 0.4 W m−1 K−1. Furthermore, the non-uniformity of local thermal conductivity and heat losses through the samples is due mainly to the non-uniform distribution of fibres inside the mixes inducing an increase in heat loss up to 50% for structural walls and 25% for insulation walls. Cob thermal properties are used in a comparative simulation case study of a typical house under French and UK climatic conditions. The energy performance of the conventional building is compared to a dual walled cob building, showing remarkable reduction in energy consumption as the cob walls, whilst maintaining comfortable indoor conditions without additional heating.

Seismic Analysis of Reinforced Concrete Buildings in the 1931 Hawke's Bay Earthquake

<p>This thesis examines current earthquake engineering theory and practice regarding Earthquake Risk Buildings to determine if the seismic performance of reinforced concrete buildings is currently underestimated. The types of structural systems investigated are: Reinforced Concrete Structural Walls Unreinforced Brick Masonry (URM) Infill Frames Reinforced Concrete Moment Resisting Frames Buildings with the above systems that survived the February 3 1931 Hawke's Bay earthquake and are still in existence are the set of buildings studied. As much structural information as possible was found for a total of 25 buildings which are analysed in two orthogonal directions. The calculated probable shear and bending strength of each structural member (at ground floor) is compared with the actual estimated seismic shear force and bending moment applied during the earthquake. The restoring moments of structural walls are compared to the calculated overturning moments. The results are expressed as ratios of the above forces and moments of each member. The thesis shows that current theory expects most buildings to fail during both the 1931 Hawke's Bay earthquake and the Code design earthquake but most performed very well with no structural damage. The thesis examines the possible causes of underestimation of seismic performance by current earthquake engineering theory and practice, and makes recommendations for refining and improving practice. Recommendations are also made for further research to establish a simple assessment method for analysing other similar buildings based on the plan area of reinforced concrete structural elements alone.</p>

Seismic Analysis of Reinforced Concrete Buildings in the 1931 Hawke's Bay Earthquake

<p>This thesis examines current earthquake engineering theory and practice regarding Earthquake Risk Buildings to determine if the seismic performance of reinforced concrete buildings is currently underestimated. The types of structural systems investigated are: Reinforced Concrete Structural Walls Unreinforced Brick Masonry (URM) Infill Frames Reinforced Concrete Moment Resisting Frames Buildings with the above systems that survived the February 3 1931 Hawke's Bay earthquake and are still in existence are the set of buildings studied. As much structural information as possible was found for a total of 25 buildings which are analysed in two orthogonal directions. The calculated probable shear and bending strength of each structural member (at ground floor) is compared with the actual estimated seismic shear force and bending moment applied during the earthquake. The restoring moments of structural walls are compared to the calculated overturning moments. The results are expressed as ratios of the above forces and moments of each member. The thesis shows that current theory expects most buildings to fail during both the 1931 Hawke's Bay earthquake and the Code design earthquake but most performed very well with no structural damage. The thesis examines the possible causes of underestimation of seismic performance by current earthquake engineering theory and practice, and makes recommendations for refining and improving practice. Recommendations are also made for further research to establish a simple assessment method for analysing other similar buildings based on the plan area of reinforced concrete structural elements alone.</p>

Analytical study on the effect of extreme seismic strains on the transverse buckling of ultra-reinforced seismic walls and their environmental design

In the context of the present work, the influence of the degree of tension on the phenomenon of transverse instability of reinforced concrete seismic walls is examined. Useful conclusions are drawn regarding the influence of the degree of elongation on the phenomenon of transverse buckling. These conclusions are substantiated both experimentally and analytically, as the results of the experiments are compared with the corresponding results of the analytical investigation. Moreover, some thoughts on a more environmental design of R/C seismic walls are stated. The present investigation is both experimental and analytical and consists of 4 test specimens. These specimens simulate the extreme boundary edges of structural walls. All columns simulate only the extreme reinforced areas of the walls, in order to study the basic mechanism of the phenomenon. The detailing of the specimens consists of 6 rebars with a diameter of 12 mm for each bar. The geometric dimensions are the same for all specimens. What differentiates the specimens from each other is the degree of tension they have sustained. More specifically, the tensile degrees used are 10‰, 20‰, 30‰ and 50‰. The loading stages of each specimen for all specimens are as follows: (a) Uniaxial central tensile loading on each test specimen apart from the specimen sustained 0‰ degree of tension; (b) Uniaxial central compression loading on each specimen till its failure due to buckling or due to an excess of its cross-section compressive strength. The present study focuses on the tensile loading stage only. Extreme tensile strengths are also used, e.g., 30‰ and 50‰, in order to take into account, the cases of extreme seismic excitations. The experimental study is followed by the numerical investigation of these 4 specimens using appropriate statistical software and finite elements.

Production of Light Weight Blocks Using Rice Husk

Affordable housing has remained a major challenge in Nigeria, as housing costs have continued to rise beyond the reach of the low income population. This paper explores the use of waste products like rice husk as alternative materials for housing construction. Rice husk is abundant as a waste product in areas where rice is processed commercially in Southeast Nigeria. The aim of the study is to create rice husk blocks that are cheap, lightweight, and appropriate for use in low income housing construction. The study was conducted through experimentation in the Building Technology workshop of Federal Polytechnic Nekede. A series of trial mixes were done involving a wide range of materials and mix proportions. Rice husk, Portland cement, and cassava starch, were found to be the most appropriate components for the blocks. The blocks produced were of good appearance, and lightweight. Five samples of solid core blocks measuring 150x150x150mm were tested in Strength of Materials laboratory of the Federal University of Technology Owerri. The average compressive strength of the blocks was 0.26N/mm2, which is below the Nigerian Industrial Standard NIS 87:2007. The blocks produced were considered appropriate for use as non-load bearing partitions and not structural walls. The result of the study is promising because the rice husk blocks help address the waste management problem in affected areas, and could also be an important component of a potentially useful material. This paper recommends further research in the area of improving the strength of the blocks, to make them usable as structural components in low rise buildings.

PKM Pemanfaatan Sekam Padi Sebagai Alternatif Campuran Material Dinding Ringan Untuk Mendukung Hunian Tahan Gempa di Kota Palu

The involvement and empowerment of communities affected by the September 28, 2018 Palu Earthquake in their home areas is an opportunity that can be taken to contribute to residential reconstruction. Currently, the rehabilitation and construction of housing requires a lot of materials that support earthquake-resistant buildings, one of which is construction materials for the walls of houses or dwellings that have light weights such as light bricks, which are mostly supplied from outside the Central Sulawesi area. For this purpose, this paper presents the results of the implementation of the Community Partnership Program (PKM) in disaster-affected communities by utilizing rice husks as light brick materials. Implementation of the program begins with socialization to prospective participants and continues with the work and testing of light brick samples, training to make lightweight bricks, monitoring and evaluation. The test results show that light brick made of a mixture of cement, husk and sand (Type II) with a volume ratio of 1:1.5:4.5 still meets the requirements as a house wall material and it is included in Quality Level III (SNI 03-0349-1989) for the use of unprotected non-structural walls, may be exposed to rain and heat with an average compressive strength of 35 kg/cm2. This type II brick is then recommended as a wall material, where this type provides a weight reduction of 54.85% from the weight of conventional bricks. A review of the results of program implementation shows that the affected communities represented by 50 respondents gave a fairly good perception of the acceptance of light bricks as wall material with a score of 3.70 of 5. Evaluation of the program showed that 80% of all respondents stated that they were skilled at making light bricks. and they will develop these material to support the reconstruction of housing in Palu