Due to the topological and geological nature of the Netherlands many areas around the country suffer from poor soil resistance which makes construction and engineering of structures increasingly difficult. Therefore, in thousands of cases around the country in different stages of a structure’s lifespan, the capacity required from the soil by structures has been insufficient. Moreover, masonry constitutes a nationally popular construction material in the Netherlands, particularly in the case of residential homes. Masonry structures are understood to be more prone to damage when they suffer changes in their structural equilibrium, this is commonly attributed to their hybrid composition and the plentiful locations for failure envelopes to develop along the discrete block interfaces in a masonry structure’s envelope. Therefore, throughout the Netherlands, thousands of homes have seen their structural integrity compromised by cracks and distortions through the introduced subsidence-led distortions. In some cases this has led to the necessity to intervene in the building’s foundation systems to prevent the effects of further subsidence effects, whereas in many other extreme cases demolition was deemed the only viable course of action. Therefore, efficient yet precise damage prediction to masonry structures due to subsidence has the potential to preemptively determine the vulnerability of structures and allow for the engineering of countermeasures to be implemented at times when intervention is still economically feasible. Therefore the tools in this repository aim to fulfil the following objective.
Project Objective: To develop and asses available methods in the evaluation of structural damage to masonry structures undergoing urban shallow subsidence
The development and analysis of analytical and numerical solutions, to preemptively determine the vulnerability of structures.
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| Figure 1: Building Numerical modelling scheme | Figure 2: Masonry structure accommodating to a subsidence surface |
In the Netherlands, it has been customary for engineering consultants to perform inspections in those buildings affected by subsidence phenomena. Their assessment and investigation eventually take the form of a foundation assessment report. In this report the inspection and posterior assessment findings are presented, its contents usually include the archival information of the building (year of construction, major remodelations..). An extensive building damage documentation presented in the form of images indicating the severity and location of the damage sustained by the building, a measurements campaign to quantify the distortions experienced by the building, usually taking the form of skew measurements at different locations in the building. Lastly, a simple soil exploration campaign to understand the capacity of the underneath soil and the location typology and dimensions of the foundation relative to the underneath strata.
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| Figure 3: Exemplary skew measurement diagram | Figure 4: Masonry structure accommodating to a subsidence surface |
From your building assessment report of self taken measurements you only require to define the basic geometry and continous layout of your building. With it is necessary to provide the subsidence measurements and their location continuously along the wall.
walls = {
'wall1':{"x": np.array([0, 0, 0]), "y": np.array([0, 3.5, 7]), "z": np.array([0, -72, -152]), 'phi': np.array([1/200,1/200]), 'height': 5000, 'thickness': 27},
'wall2':{"x": np.array([0, 4.5, 8.9]), "y": np.array([7, 7, 7]), "z": np.array([-152, -163, -188]), 'phi': np.array([1/33,1/50]), 'height': 5000, 'thickness': 27},
'wall3':{"x": np.array([8.9, 8.9]), "y": np.array([3.6, 7]), "z": np.array([-149, -188]), 'phi': np.array([0,0]), 'height': 5000, 'thickness': 27},
'wall4':{"x": np.array([8.9, 10.8]), "y": np.array([3.6, 3.6]), "z": np.array([-149,-138]), 'phi': np.array([0,0]), 'height': 5000, 'thickness': 27},
'wall5':{"x": np.array([10.8, 10.8]), "y": np.array([0, 3.6]), "z": np.array([-104, -138]), 'phi': np.array([1/77,1/67]), 'height': 5000, 'thickness': 27},
'wall6':{"x": np.array([0, 5.2, 6.4, 8.9, 10.8]), "y": np.array([0, 0, 0, 0, 0]), "z": np.array([0, -42, -55, -75, -104]), 'phi': np.array([1/100,1/100]), 'height': 5000, 'thickness': 27},
}
ijsselsteinseweg = house(measurements = walls)Estimate the Soil related intensity factors through the SRI method:
ijsselsteinseweg.SRI()which produces the following output,
| Smax | dSmax | D/L | drat | omega | phi | beta | |
|---|---|---|---|---|---|---|---|
| 0 | 152 | 152 | 21.714286 | 4.000 | 1.524776 | 1.524776 | 3.049552 |
| 1 | 188 | 36 | 4.044944 | 7.202 | 1.328434 | 1.328434 | 2.656867 |
| 2 | 188 | 39 | 11.470588 | 0.000 | 1.483837 | 1.483837 | 0.000000 |
| 3 | 149 | 11 | 5.789474 | 0.000 | 1.399757 | 1.399757 | 0.000000 |
| 4 | 138 | 34 | 9.444444 | 0.000 | 1.465307 | 1.465307 | 0.000000 |
| 5 | 104 | 104 | 9.629630 | 10.704 | 1.467321 | 1.467321 | 2.934642 |
Table 1: Settlement related intensity factors
Aproximate and reconstruct the displacement surface of the building by first interpolating the buildings displacement field house.interpolate() then fit your prefered charateristic soil displacement equation by default it makes use of guassian_shape:
def gaussian_shape(x, s_vmax, x_inflection):
gauss_func = s_vmax * exp(-x**2/ (2*x_inflection**2))
return gauss_functhen use the house.fit_function method to estimate the nearby soil subsidence surface.
ijsselsteinseweg.fit_function(i_guess = 1, tolerance = 1e-2, step = 1) # Fit gaussian shapes to walls
plots.subsidence(ijsselsteinseweg, building = False, soil= True, deformation= True)The surface can the be visualised as follows,
Figure 5: Visualised aproximated soil surface for Ijsselsteinseweg 77.
The bricks module currently provides two main functionalities to assess a building, one is through a compilation of empirical methods i.e empirical correlations that have been determined by researchers linking the amount of damage expected in a building due to its current situation. And secondly the LTSM a elementary structural mechanical approach the displacement and strains of the building subject to a subsidence distribution.
Firstly it asseses the buildings vulnerability through a compilation of state-of-the-art limits gathered from different sources empirical_limits.py which are then evaluated through the Empirical methods 'EM()' function against a dictionary of SRI parameters. When making use of the 'house' class and having made use of the SRI() method the function can be called as follows,
ijsselsteinseweg.SRI()
report = EM(ijsselsteinseweg.soil['sri'])
app = plots.EM_plot(report)
app.run_server(debug=False)The output will be a report with the assessment state source and SRI parameter evaluated. As can be seen above the making use of bricks.tools the EM_plot() can be called which will help you visualise the assessments reports. An example of the above is the following,
Figure 6: Visualisation matrix of results from different assessment methods
The second main available assessment method is the LTSM. This method was devised by Burland & Wroth (1974) and was then expanded by other researchers such as Boscardin & Cording (1989). This method schematises a building or wall as an equivalent masonry beam and a Timoschenko beam formulation from which the subsidence through is applied. From here onwards the hogging and sagging regions of the before estimated gaussian settlement troughs are calculated and the estimation of the building strains is performed. The following is an example of use of its relevant methods.
limit_line = -1
eg_rat = 11 ## May vary # Calibrate
LTSM(ijsselsteinseweg, limit_line, eg_rat, save = True)
app = plots.LTSM_plot(ijsselsteinseweg)
app.run_server(debug=False)The produced plot when performing the evaluation is the following,
Figure 7: Visualisation of LTSM
Bricks is a in development module which aims to help engineers and homeowners in the netherlands be able to evaluate the vulnerability of their houses through accessible easy to use tools. The module has three main components.
house: A class which allows you to create an object of your own house and also provides the basic functionalities to process your building's soil and structural characteristic values relevant to the posterior analysis.bricks.assessment: Sub-module that contains the state-of-the-art analysis techniques relevant to perform a pre-emptive assessment of your structure. The current available methods available 'assess.py' are the LTSM and a compilation of empirically determined thresholds of a structures KPI's. Although effective it is important to note some of these tools lack the precision of other FEM counterparts and aim to serve as tools for educated decision making for accessible vulnerability assessment or to determine the necessity of more precise assessment methods to be employed.bricks.tools: Sub-module that contains primarily the tools to visualise the different assessment methods performed and to visualise the current state of your building.
In addition the main directory contains Ijsselsteinseweg 77.ipynb a exemplary notebook which illustrates how to perform the assessment of your building and how to utilise the visualisation tools available from 'bricks'. This is carried out through analysis of a real world scenario.