---------------------------------
190711_150x75x10_uneq-L_calcs.txt
---------------------------------

(load-file "/Users/rds/Dropbox/files_ma/computing/programs_engineering/ma2nd_shapes.el")
(load-file "/Users/rds/Dropbox/files_ma/computing/programs_engineering/ma2nd_parallelaxix.el")

;; Thursday 11 July 2019  21:41

;; load-capacity of deck I am making for drilling off front of
;; barge...

;; find neutral axis

;; n=sum(M)/sum(A)
;; take base of section - in "L" presentation

;; stay in mm for now
(/f (+ (* 65 10 5) (* 150 10 75)) (+ (* 65 10) (* 150 10)))
;; 53.83720930232558 ;; mm (! - not metres!)

(let ((a1 (* 65 10))(y1 5)(a2 (* 150 10))(y2 75))
  ;; (cons a1 a2))
  (/f (+ (* a1 y1)(* a2 y2))(+ a1 a2)))
;; 53.83720930232558

 (+
  (ma2nd-rect-b-h-cx 10e-3 150e-3) ;; 2.8124999999999993e-06
  ;; (* 10e-3 75e-3 (expt (- 150e-3 53.83720930232558e-3) 2)) ;; 6.935461736073553e-06
  (ma2nd-a-y-parallelaxis (* 10e-3 150e-3)(- 75e-3 53.83720930232558e-3)) ;; 6.717955651703624e-07
  (ma2nd-rect-b-h-cx 65e-3 10e-3) ;; 5.416666666666668e-09
  (ma2nd-a-y-parallelaxis (* 65e-3 10e-3)(- 5e-3 53.83720930232558e-3)) ;; 1.5502974580854517e-06
  ) ;; 5.04000968992248e-06 ;; m^4

;; "Blue Book" => 501cm^4 => 501e-8 = 5.01e-06m^4
;; so agrees.

;; sigma_max=My/I
;; M_max=sigma_yield I / y

(/f (* 275e6 5.04000968992248e-06)(- 150e-3 53.83720930232558e-3))
;; 14413.086960902861
;; = 14.4kNm

;; point load at middle of deck = 2.44/2+0.450
(+ (/ 2.44 2) 0.45)
;; 1.67

(*
 (/f 14413.086960902861 1.67 9.81)
 2 ;; there are two beams
 )
;; 1759.5496421106243 ;; kg-f

;; if at end of deck
(*
 (/f 14413.086960902861 (+ 2.44 0.45) 9.81)
 2 ;; there are two beams
 )
;; 1016.7639800431634
;; 1 Tonne for even at tip (front) of deck


----------------------------
190710_60x40x3_RHS_calcs.txt
----------------------------

(-
 (ma2nd-rect-b-h-cx 40e-3 60e-3)
 (ma2nd-rect-b-h-cx (* (- 40 3 3) 1e-3)(* (- 60 3 3) 1e-3))
 ) ;; 2.7385199999999993e-07 ;; m^4

(* 2.7385199999999993e-07 (expt 100 4)) ;; 27.385199999999994 ;; cm^4
;; agrees with "blue book"


--------------------------------------------------------------
230525 - getting Z, M_max not explained then - calculated here
--------------------------------------------------------------

(*
 355e6
 (z-rhs-b-h-t 40e-3 60e-3 3e-3) ;; 9.128399999999997e-06 ;; m^3
 ) ;; 3240.581999999999 ;; Nm


-----------------------------------------------
190710_loadcap_60x40RHS_2p44l_dblsup_190713.txt
-----------------------------------------------

;; M=WL/4 -> W=4M/L
(/ (* 4 3240.581999999999) 2.44 9.81) ;; 541.5320599588908

;; My first-principles calc for pure rectangular shapes gives this -
;; 542kg - for 60x40x3 S355