Update general loads 3

book/design_workflow/general_loads/variable_loads_3_rain_snow.ipynb

@@ -4,9 +4,66 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Variable loads 3: rain and snow\n",
+    "# Variable loads 3: rain and snow"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Loading by rainwater\n",
+    "Loads by rainwater are the result of accumulating water due to for example\n",
+    "hogging of adjacent roof parts or clogging of the drainage systems.\n",
+    "The most practical way of dealing with these actions is converting the snow\n",
+    "load to a layer of water (e.g.: 0,56 kN/ m2 equals 56 mm water on the roof)\n",
+    "and preventing the water from rising above this amount by designing for\n",
+    "emergency overflow. Furthermore, always design a roof with a small pitch (general loads, general)\n",
     "\n",
-    "\n"
+    "```{figure} Images/Emergency overflow.jpg\n",
+    "---\n",
+    "scale: 100%\n",
+    "---\n",
+    "Emergency overflow by means of a so called \"mailbox\"\n",
+    "```\n",
+    "\n",
+    "```{figure} Images/Emergency overflow 2.jpg\n",
+    "---\n",
+    "scale: 100%\n",
+    "---\n",
+    "```"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Snow loads\n",
+    "Snow can cause considerable loads, as it doesn’t run off like rain. It is therefore important to check whether a load combination containing snow\n",
+    "loads is leading. For different parts of Europe the value of the snow load can differ greatly (e.g.: compare the Mediterranean Coast to the Alps). In\n",
+    "the Dutch National Annex of NEN-EN 1991-1-3 the complex calculations are substituted by one value for the whole country (sk = 0,7 kN/m2). For other areas NEN-EN 1991-1-3 must be consulted."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Determining the snow loading\n",
+    "\n",
+    "$s = μ_i · C_e · C_t · s_k$\n",
+    "  \n",
+    "$s$ = Characteristic value of the snow load on the ground [$kN/m^2$] ($0,7 kN/m^2$ in\n",
+    "the Netherlands)  \n",
+    "$μ_i$ = Shape coefficient, dependend on roof angle α  \n",
+    "$C_e$ = Exposure coefficient (1,0 for most cases)  \n",
+    "$C_t$ = Thermal coefficient (1,0 for most cases)  \n",
+    "  \n",
+    "The shape coefficient can be determined with the shown diagram. Note that μ2 is only applicable where snow accumulation can occur. For complex roof shapes and more information, see NEN-EN 1991-1-3.\n",
+    "\n",
+    "```{figure} Images/Snow loading.jpg\n",
+    "---\n",
+    "scale: 100%\n",
+    "---\n",
+    "```"
    ]
   },
   {