Add structural calculation worksheets

Collection of engineering calculation projects (Python + Typst), each with
input, calc script, tests, results, and generated PDF where available.

concrete-beam/results.json

@@ -0,0 +1,49 @@
+{
+  "tool": "concrete_beam",
+  "version": "0.1",
+  "project": "Deer Creek Shoring",
+  "prepared_by": "Conemco Engineering",
+  "values": {
+    "span_ft": 16.0,
+    "tributary_ft": 6.25,
+    "D_psf": 55.0,
+    "L_psf": 20.0,
+    "self_weight_klf": 0.1,
+    "wD_klf": 0.44375,
+    "wL_klf": 0.125,
+    "wu_klf": 0.7325,
+    "Mu_kipft": 23.44,
+    "Vu_kip": 5.86,
+    "bw_in": 8.0,
+    "h_in": 12.0,
+    "d_in": 9.5,
+    "fc_ksi": 3.0,
+    "fy_ksi": 60.0,
+    "As_in2": 0.62,
+    "a_in": 1.823529,
+    "et": 0.010285,
+    "phi": 0.9,
+    "Mn_kipft": 26.623529,
+    "phiMn_kipft": 23.961176,
+    "As_min_in2": 0.253333,
+    "Vc_kip": 8.325383,
+    "phiVc_kip": 6.244037
+  },
+  "checks": {
+    "flexure": {
+      "demand": 23.44,
+      "capacity": 23.961176,
+      "ok": true
+    },
+    "minimum_steel": {
+      "demand": 0.253333,
+      "capacity": 0.62,
+      "ok": true
+    },
+    "shear": {
+      "demand": 5.86,
+      "capacity": 6.244037,
+      "ok": true
+    }
+  }
+}