# Knowledge Management in Construction Health and Safety Based on Ontology Modeling
## 5 Case Study
### Rule Development  
As presented above, OWL can accurately describe the ontological knowledge of H&S management. However, it cannot be leveraged to express the knowledge rules, e.g., the standards and regulations involved in H&S management. As a standard rule-based semantic language initiated by W3C, SWRL is proposed to represent the domain of health-and-safety-related regulations and standards by successfully integrating domain safety  
Figure 10: Consistency checking using Pellet reasoner. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Question** & \begin{tabular}{c} **Very** \\ **Agree (5)** \\ \end{tabular} & \begin{tabular}{c} **Agree** \\ **(4)** \\ \end{tabular} & \begin{tabular}{c} **Neutral** \\ **(3)** \\ \end{tabular} & \begin{tabular}{c} **Disagree** \\ **(2)** \\ \end{tabular} & \
\begin{tabular}{c} **Very** \\ **Disagree (1)** \\ \end{tabular} &
\begin{tabular}{c} **Means/Result** \\ **Means/Result** \\ \end{tabular} \\ \hline How easy do you think to understand & 10\% & 60\% & 30\% & 0 & 0 & 3.8”Easy” \\ and navigate through the HSM-Onto & 10\% & 60\% & 30\% & 0 & 0 & 3.8”Easy” \\ \hline Are you familiar with the concepts in & & & & & & \\ the HSM-Onto that convey their & 40\% & 50\% & 10\% & 0 & 0 & 4.3 ”Familiar” \\ intended meanings? & & & & & & \\ \hline Can the HSM-Onto improve the safety & 50 & 50 & 0 & 0 & 0 & 4.5 ”Agree” \\ management decision-making? & & & & & & \\ \hline Can the HSM-ONTO reduce the risk & 20 & 50 & 30 & 0 & 0 & 3.9”Agree” \\ events on construction sites? & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._knowledge into the logic rules. In this case study, using HSM-Onto concepts, the removal of formwork in Eurocode 2 (Design of Concrete Structures) was first integrated into SWRL rules. The following examples show (1) the requirement of formwork for slab casting to avoid the risk of \"collapse\" and (2) minimum formwork stripping time under different temperatures. The objects and attributes in the following SWRL rules are demonstrated in Figure 11.  
**Eurocode 2: DCS Regulation:**  
_\"6.3.2.1 P(1) Formwork and falsework shall be designed and constructed so that they are capable of resisting all actions which may occur during the construction process. They shall remain undisturbed until the concrete has achieved sufficient strength to withstand the stresses to which it will be subjected to stripping or release, with an acceptable margin of safety.\"_  
The stripping time for slab softits is shown in Table 4 when the cement used for slab concrete is O.P.C 33 grade (ISI-269), OPC-43 grade (ISI-8112) and PPC Cement (ISI-1489) and the span of the slab is under 3.6m (Table 4). _The Logic Rule Here is:_  
_Rule 1. If the temperature is \(T>\) 20 \({}^{\circ}\)C, then the stripping time of slab softfits should be at least 11 days._  
The SWRL rules of the above can be written like this:_  
_Construction_Activity(Formwork_Slab_Soffits)^Consistent_of(Formwork_Slab_Soffits,?SC)^-  
_Slab_Casting(?SC)^has_produced(?SC,?S)^Slab(?S)^has_precursor(?SC,?RP)^Risk_Precursor (?RP)^temperature(?RP,?T)^swrlb:greaterThan(?T,20)>has_risk(?R,collapse)^has_mitigation (?R,formwork)^has_period(?R,11)_  
_Rule 2. If the temperature is 12 \({}^{\circ}\)C \(<\) T \(<\) 20 \({}^{\circ}\)C, the stripping time of slab softfits should be at least 17 days._  
The SWRL rules of the above can be written as:  
Figure 11: Slab Casting task-related classes and attributes used in SWRL rules 1, 2 and 3. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Formed Surface** & **Hot Conditions** & **Average Conditions** & **Cold Conditions** \\  & **\textgreater{}20 \({}^{\circ}\)C** & \textless{}2 \({}^{\circ}\)C\textgreater{}1 \({}^{\circ}\)C** & \textless{}**12 \({}^{\circ}\)C** \\ \hline Slab softits & 11 days & 17 days & 23 days \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Minimum Formwork Stripping Times for Slab Softits.